Rasterization block what. Wise choice of video card
The fill rate shows how fast the video chip is capable of drawing pixels. There are two types of fillrate: pixel fill rate and texture fill rate. Pixel fill rate shows the speed of drawing pixels on the screen and depends on the operating frequency and the number of ROP units (rasterization and blending operation units), and texture fill rate is the speed of sampling texture data, which depends on the operating frequency and the number of texture units.
For example, the pixel fillrate of the GeForce GTX 275 is 633 (chip frequency) * 28 (number of ROP units) = 17724 megapixels per second, and the texture fillrate is 633 * 80 (number of texturing units) = 50640 megatexels/s. The larger the first number, the faster the video card can draw finished pixels, and the larger the second, the faster the texture data is sampled. Both parameters are important for modern games, but they must be balanced. This is why the number of ROP units in modern chips is usually less than the number of texture units.
Number of shader blocks (pixel, vertex).
The vertex shader is responsible for constructing the vertices of an object. They determine the capabilities of modern cards for processing graphic primitive objects, and in general the performance of the card itself. A pixel shader is more relevant than a vertex shader, so their number is usually greater. The division into pixel and vertex has recently (with the release of Direct 10) lost its relevance. All of them are replaced by single unified shader blocks, depending on the specific situation. They use both pixel and vertex shaders, as well as geometric ones, which appeared in Direct 10.
Number of TMU texturing units
The number of TMU texturing units that determine texture performance, or the speed at which textures are sampled and mapped. This is especially relevant for anisotropic filtering. TMU blocks are most important in older games. Now they have practically lost their relevance, because... The memory bus bandwidth in modern systems is not enough for high-performance cards to function normally. Most of them are equipped with their own memory, which is required to store the necessary data, namely textures, vertices, etc.
Rasterization Operation Units (ROPs)
Rasterization units carry out the operations of writing pixels calculated by the video card into buffers and the operations of mixing them (blending). As we noted above, the performance of ROP blocks affects the fill rate and this is one of the main characteristics of video cards of all times. And although its importance has also decreased somewhat recently, there are still cases where application performance depends on the speed and number of ROP blocks. Most often this is due to the active use of post-processing filters and anti-aliasing enabled at high game settings.
Let us note once again that modern video chips cannot be assessed only by the number of different blocks and their frequency. Each GPU series uses a new architecture, in which the execution units are very different from the old ones, and the ratio of the number of different units may differ. Thus, AMD ROP units in some solutions can perform more work per clock cycle than units in NVIDIA solutions, and vice versa. The same applies to the capabilities of TMU texture units - they are different in different generations of GPUs from different manufacturers, and this must be taken into account when comparing.
Geometric blocks
Until recently, the number of geometry processing units was not particularly important. One block on the GPU was enough for most tasks, since the geometry in games was quite simple and the main focus of performance was mathematical calculations. The importance of parallel geometry processing and the number of corresponding blocks increased dramatically with the advent of geometry tessellation support in DirectX 11. NVIDIA was the first to parallelize the processing of geometric data when several corresponding blocks appeared in its GF1xx family chips. Then, AMD released a similar solution (only in the top solutions of the Radeon HD 6700 line based on Cayman chips).
Video memory size
Own memory is used by video chips to store the necessary data: textures, vertices, buffer data, etc. It would seem that the more there is, the better. But it’s not so simple; estimating the power of a video card based on the amount of video memory is the most common mistake! Inexperienced users most often overestimate the value of video memory, and still use it for comparison different models video cards This is understandable - this parameter is one of the first to be indicated in the lists of characteristics of finished systems, and it is written in large font on video card boxes. Therefore, it seems to an inexperienced buyer that since there is twice as much memory, then the speed of such a solution should be twice as high. The reality differs from this myth in that memory comes in different types and characteristics, and productivity growth grows only up to a certain volume, and after reaching it simply stops.
Memory chips have more important parameters, such as the memory bus width and its operating frequency.
Memory bus width.
The memory bus width is the most important characteristic affecting memory bandwidth (MBB). A larger width allows more information to be transferred from video memory to the GPU and back per unit time, which has a positive effect on performance in most cases. Theoretically, a 256-bit bus can transfer twice as much data per clock cycle as a 128-bit bus. In practice, the difference in rendering speed, although it does not reach two times, is very close to this in many cases with an emphasis on video memory bandwidth.
Modern gaming video cards use different bus widths: from 64 to 384 bits (previously there were chips with a 512-bit bus), depending on the price range and release time of a particular GPU model. For the cheapest low-end video cards, 64 and less often 128 bits are most often used, for the middle level from 128 to 256 bits, and video cards from the upper price range use buses from 256 to 384 bits wide. The bus width can no longer grow purely due to physical limitations - the GPU die size is insufficient to accommodate more than a 512-bit bus, and this is too expensive. Therefore, memory bandwidth is now being increased by using new types of memory (see below).
Video memory frequency
Another parameter that affects memory bandwidth is its clock frequency. And increasing the bandwidth often directly affects the performance of the video card in 3D applications. The memory bus frequency on modern video cards ranges from 533 (1066, taking into account doubling) MHz to 1375 (5500, taking into account quadrupling) MHz, that is, it can differ by more than five times! And since bandwidth depends on both the memory frequency and the width of its bus, memory with a 256-bit bus operating at a frequency of 800 (3200) MHz will have greater bandwidth compared to memory operating at 1000 (4000) MHz with a 128-bit bus.
Memory types
Modern video cards are equipped with several different types of memory. You won't find old single-speed SDR memory anywhere anymore, but modern types of DDR and GDDR memory have significantly different characteristics. Various types of DDR and GDDR allow you to transfer two or four times more data at the same clock frequency per unit time, and therefore the operating frequency figure is often doubled or quadrupled, multiplied by 2 or 4. So, if the frequency is specified for DDR memory 1400 MHz, then this memory operates at a physical frequency of 700 MHz, but they indicate the so-called “effective” frequency, that is, the one at which the SDR memory must operate in order to provide the same bandwidth. The same thing with GDDR5, but the frequency is even quadrupled.
The main advantage of new types of memory is the ability to operate at higher clock speeds, and, accordingly, an increase in bandwidth compared to previous technologies. This is achieved at the expense of increased latencies, which, however, are not so important for video cards.
It follows that the larger the video card memory, the higher the performance. Important parameters are the bus operating frequency and bus width. A larger bus width allows more information to be transferred per unit of time from video memory to the GPU and back. This ensures greater video card performance under equal conditions. The bus width is 64-128 bits for a budget video card, 128-256 bits for mid-range cards, for high level– 256-512 bits.
1.2 Description of the operation and block diagram of the device
When constructing an image, after processing the video signal by the central processor, the data is sent to the video card data bus. Next, the data is sent to the parallel command execution unit, and from it to the GPU (graphics processor), in which the following actions are performed:
· Transformation - simple objects most often need to be changed or transformed in a certain way to create a more natural object, or to imitate its movement in space. To do this, the coordinates of the vertices of the object's faces (vertex) are recalculated using matrix algebra operations and geometric transformations. In video cards it is intensively used for this purpose. geometric coprocessor.
· Calculation of illumination and shading - in order for an object to be visible on the screen, it is necessary to calculate the illumination and shading of each elementary rectangle or triangle. Moreover, it is necessary to simulate the real distribution of illumination, i.e., it is necessary to hide changes in illumination between rectangles or triangles - this is done by the Rasterization Unit.
· Texture mapping - to create a realistic image, a texture is applied to each elementary surface that imitates the real surface. Textures are stored in memory as raster images.
· Correction of defects - simulated lines and boundaries of objects, if they are not vertical or horizontal, look angular on the screen, so an image correction is carried out, called antialiasing ( anti-aliasing);
After GPU processing, objects are processed by the “Z-buffer” block:
· Projection - a three-dimensional object is converted into a two-dimensional one, but the distances of the vertices of the faces to the surface of the screen (Z coordinate, Z-buffer) onto which the object is projected are remembered;
· Removing hidden surfaces - removes all invisible surfaces from a 2D projection of a 3D object.
After calculating all points in the frame, information about each pixel is moved to video memory.
In the palette and image overlay control block, the missing colors are interpolated - if a different number of colors were used when modeling objects than in the current video card mode, then it is necessary to calculate the missing colors or remove the redundant ones.
If the video card is connected to a monitor based on a cathode ray tube, then the data goes to a DAC (digital-to-analog converter) in which digital signals are converted into analog RGB signals understandable to the monitor.
If the video card is connected to a digital monitor, then the image information is converted to the monitor screen format.
Basic components of a video card:
- exits;
- interfaces;
- cooling system;
- GPU;
- video memory.
Graphics technologies:
- dictionary;
- GPU architecture: features
vertex/pixel units, shaders, fill rate, texture/raster units, pipelines; - GPU architecture: technology
technical process, GPU frequency, local video memory (volume, bus, type, frequency), solutions with multiple video cards; - visual functions
DirectX, high dynamic range (HDR), full-screen anti-aliasing, texture filtering, high-resolution textures.
Glossary of basic graphic terms
Refresh Rate
Just like in a movie theater or TV, your computer simulates motion on the monitor by displaying a sequence of frames. The monitor's refresh rate indicates how many times per second the image on the screen will be updated. For example, a frequency of 75 Hz corresponds to 75 updates per second.
If the computer processes frames faster than the monitor can output, then problems may occur in games. For example, if the computer renders 100 frames per second, and the monitor's refresh rate is 75 Hz, then due to overlaps, the monitor can only display part of the image during its refresh period. As a result, visual artifacts appear.
As a solution, you can enable V-Sync (vertical sync). It limits the number of frames the computer can output to the monitor's refresh rate, preventing artifacts. If you enable V-Sync, the number of frames calculated in the game will never exceed the refresh rate. That is, at 75 Hz the computer will output no more than 75 frames per second.
Pixel
The word "Pixel" stands for " pic ture el ement" - image element. It is a tiny dot on the display that can glow in a certain color (in most cases, the hue is displayed by a combination of three basic colors: red, green and blue). If the screen resolution is 1024x768, then you can see a matrix of 1024 pixels in width and 768 pixels in height. All the pixels together make up the image. The image on the screen is updated from 60 to 120 times per second, depending on the type of display and the data output from the video card. CRT monitors refresh the display line by line, while flat panel LCD monitors can refresh each pixel individually.
Vertex
All objects in a 3D scene are made up of vertices. A vertex is a point in three-dimensional space with coordinates X, Y and Z. Several vertices can be grouped into a polygon: most often it is a triangle, but more complex shapes are possible. A texture is then applied to the polygon, which makes the object look realistic. The 3D cube shown in the illustration above consists of eight vertices. More complex objects have curved surfaces that are actually made up of a very large number of vertices.
Texture
A texture is simply a 2D image of an arbitrary size that is mapped onto a 3D object to simulate its surface. For example, our 3D cube consists of eight vertices. Before applying the texture, it looks like a simple box. But when we apply the texture, the box becomes colored.
Shader
Pixel shader programs allow the video card to produce impressive effects, for example, like this water in Elder Scrolls: Oblivion.
Today there are two types of shaders: vertex and pixel. Vertex shader programs can modify or transform 3D objects. Pixel shader programs allow you to change the colors of pixels based on some data. Imagine a light source in a 3D scene that causes illuminated objects to glow brighter, while at the same time causing shadows to be cast on other objects. All this is achieved by changing the color information of the pixels.
Pixel shaders are used to create complex effects in your favorite games. For example, shader code can make the pixels surrounding a 3D sword glow brighter. Another shader can process all the vertices of a complex 3D object and simulate an explosion. Game developers are increasingly turning to sophisticated shader programs to create realistic graphics. Almost every modern game with rich graphics uses shaders.
With the release of the next Application Programming Interface (API), Microsoft DirectX 10, a third type of shader will be released, called geometry shaders. With their help, it will be possible to break objects, modify and even destroy them, depending on the desired result. The third type of shaders can be programmed in exactly the same way as the first two, but its role will be different.
Fill Rate
Very often on the box with a video card you can find the fill rate value. Basically, fill rate indicates how fast the GPU can output pixels. Older video cards had a triangle fill rate. But today there are two types of fill rates: pixel fill rate and texture fill rate. As already mentioned, the pixel fill rate corresponds to the pixel output rate. It is calculated as the number of raster operations (ROP) multiplied by the clock frequency.
Texture fill rate is calculated differently by ATi and nVidia. Nvidia believes that speed is obtained by multiplying the number of pixel pipelines by the clock frequency. And ATi multiplies the number of texture units by the clock speed. In principle, both methods are correct, since nVidia uses one texture unit per pixel shader unit (that is, one per pixel pipeline).
With these definitions in mind, let us move on and discuss the most important functions of the GPU, what they do and why they are so important.
GPU Architecture: Features
The realism of 3D graphics greatly depends on the performance of the video card. The more pixel shader blocks the processor contains and the higher the frequency, the more effects can be applied to the 3D scene to improve its visual perception.
The GPU contains many different functional blocks. By the number of some components, you can estimate how powerful the GPU is. Before moving further, let us review the most important functional blocks.
Vertex processors (vertex shader units)
Like pixel shader units, vertex processors execute shader code that touches vertices. Because a larger vertex budget allows for more complex 3D objects to be created, the performance of vertex processors is very important in 3D scenes with complex or large numbers of objects. However, vertex shader units still do not have such an obvious impact on performance as pixel processors.
Pixel processors (pixel shader units)
A pixel processor is a component of a graphics chip dedicated to processing pixel shader programs. These processors perform calculations that concern only pixels. Because pixels contain color information, pixel shaders allow you to achieve impressive graphical effects. For example, most of the water effects you see in games are created using pixel shaders. Typically, the number of pixel processors is used to compare the pixel performance of video cards. If one card has eight pixel shader units and another has 16 units, then it is logical to assume that a video card with 16 units will be faster at processing complex pixel shader programs. Clock speed should also be taken into account, but today doubling the number of pixel processors is more energy efficient than doubling the frequency of the graphics chip.
Unified shaders
Unified shaders have not yet arrived in the PC world, but the upcoming DirectX 10 standard is based on a similar architecture. That is, the code structure of vertex, geometry and pixel programs will be the same, although shaders will perform different work. The new specification can be seen in the Xbox 360, where the GPU was specially designed by ATi for Microsoft. It will be very interesting to see what potential the new DirectX 10 brings.
Texture Mapping Units (TMU)
Textures should be selected and filtered. This work is done by texture mapping units, which work in conjunction with pixel and vertex shader units. The TMU's job is to apply texture operations to pixels. The number of texture units in a GPU is often used to compare the texture performance of video cards. It's reasonable to assume that a graphics card with more TMUs will give better texture performance.
Raster Operator Units (ROP)
Raster processors are responsible for writing pixel data to memory. The speed at which this operation is performed is the fill rate. In the early days of 3D accelerators, ROP and fill rate were very important characteristics of video cards. Today, ROP work is still important, but video card performance is no longer limited by these blocks as it once was. Therefore, the performance (and number) of ROPs is rarely used to evaluate the speed of a video card.
Conveyors
Pipelines are used to describe the architecture of video cards and give a very clear idea of the performance of the GPU.
Conveyor cannot be considered a strict technical term. The GPU uses different pipelines that perform different functions. Historically, a pipeline meant a pixel processor that was connected to its texture mapping unit (TMU). For example, the Radeon 9700 video card uses eight pixel processors, each of which is connected to its own TMU, so the card is considered to have eight pipelines.
But modern processors are very difficult to describe by the number of pipelines. Compared to previous designs, the new processors use a modular, fragmented structure. ATi can be considered an innovator in this area, which, with the X1000 line of video cards, switched to modular structure, which made it possible to achieve performance gains through internal optimization. Some CPU blocks are used more than others, and to improve GPU performance, ATi has tried to find a compromise between the number of blocks needed and the die area (which can't be increased very much). In this architecture, the term “pixel pipeline” has already lost its meaning, since the pixel processors are no longer connected to their own TMUs. For example, the ATi Radeon X1600 GPU has 12 pixel shader units and only four TMU texture mapping units. Therefore, it is impossible to say that the architecture of this processor has 12 pixel pipelines, just as it is impossible to say that there are only four of them. However, by tradition, pixel pipelines are still mentioned.
Taking into account the above assumptions, the number of pixel pipelines in a GPU is often used to compare video cards (with the exception of the ATi X1x00 line). For example, if you take video cards with 24 and 16 pipelines, then it is quite reasonable to assume that the card with 24 pipelines will be faster.
GPU Architecture: Technology
Technical process
This term refers to the size of one element (transistor) of the chip and the accuracy of the manufacturing process. Improvements in technical processes make it possible to obtain smaller sized elements. For example, the 0.18 micron process produces larger features than the 0.13 micron process, so it is not as efficient. Smaller transistors operate at lower voltage. In turn, a decrease in voltage leads to a decrease in thermal resistance, which results in a decrease in the amount of heat generated. Improvements in the technical process make it possible to reduce the distance between the functional blocks of the chip, and data transfer takes less time. Shorter distances, lower voltages, and other improvements allow higher clock speeds to be achieved.
What complicates the understanding somewhat is that today both micrometers (μm) and nanometers (nm) are used to designate a technical process. In fact, everything is very simple: 1 nanometer is equal to 0.001 micrometer, so 0.09-μm and 90-nm processes are the same thing. As noted above, a smaller process technology allows for higher clock speeds. For example, if we compare video cards with 0.18 micron and 0.09 micron (90 nm) chips, then it is quite reasonable to expect a higher frequency from a 90 nm card.
GPU clock speed
GPU clock speed is measured in megahertz (MHz), which is millions of clock cycles per second.
Clock speed directly affects GPU performance. The higher it is, the more work can be done in a second. For the first example, let's take the nVidia GeForce 6600 and 6600 GT video cards: the 6600 GT GPU runs at 500 MHz, while the regular 6600 card runs at 400 MHz. Since the processors are technically identical, the 6600 GT's 20% increase in clock speed results in higher performance.
But clock speed is not everything. Keep in mind that performance is greatly influenced by architecture. For the second example, let's take the GeForce 6600 GT and GeForce 6800 GT video cards. The 6600 GT GPU clocks at 500 MHz, but the 6800 GT runs at just 350 MHz. Now let's take into account that the 6800 GT uses 16 pixel pipelines, while the 6600 GT uses only eight. Therefore, a 6800 GT with 16 pipelines at 350 MHz will give approximately the same performance as a processor with eight pipelines and double the clock speed (700 MHz). With that said, clock speed can easily be used to compare performance.
Local video memory
Video card memory greatly affects performance. But different memory parameters have different effects.
Video memory size
The amount of video memory can probably be called the most overestimated parameter of a video card. Inexperienced consumers often use video memory capacity to compare different cards with each other, but in reality, capacity has little effect on performance compared to parameters such as memory bus frequency and interface (bus width).
In most cases, a card with 128 MB of video memory will perform almost the same as a card with 256 MB. Of course, there are situations where more memory will improve performance, but keep in mind that more memory will not automatically lead to faster gaming speeds.
Where volume can be useful is in games with high-resolution textures. Game developers provide several sets of textures for the game. And the more memory there is on the video card, the higher resolution the loaded textures can have. High resolution textures provide greater clarity and detail in the game. Therefore, it is quite reasonable to take a card with a large amount of memory, if all other criteria match. Let us remind you once again that the width of the memory bus and its frequency have a much stronger impact on performance than the amount of physical memory on the card.
Memory bus width
Memory bus width is one of the most important aspects of memory performance. Modern buses range from 64 to 256 bits wide, and in some cases even 512 bits. The wider the memory bus, the more information it can transfer per clock cycle. And this directly affects productivity. For example, if you take two buses with equal frequencies, then theoretically a 128-bit bus will transfer twice as much data per clock cycle as a 64-bit bus. And the 256-bit bus is twice as big.
Higher bus bandwidth (expressed in bits or bytes per second, 1 byte = 8 bits) gives higher memory performance. This is why the memory bus is much more important than its size. At equal frequencies, the 64-bit memory bus operates at a speed of only 25% of the 256-bit one!
Let's take the following example. A video card with 128 MB of video memory, but with a 256-bit bus, gives much higher memory performance than a 512 MB model with a 64-bit bus. It is important to note that for some cards from the ATi X1x00 line, manufacturers indicate the specifications of the internal memory bus, but we are interested in the parameters of the external bus. For example, the X1600 has an internal ring bus that is 256 bits wide, but an external one that is only 128 bits wide. And in reality, the memory bus operates at 128-bit performance.
Memory types
Memory can be divided into two main categories: SDR (single data transfer) and DDR (double data transfer), in which data is transferred twice as fast per clock cycle. Today, single transmission SDR technology is obsolete. Since DDR memory transfers data twice as fast as SDR, it is important to remember that video cards with DDR memory most often indicate double the frequency, not the physical one. For example, if DDR memory is specified at 1000 MHz, then this is the effective frequency at which regular SDR memory must operate to give the same throughput. But in fact, the physical frequency is 500 MHz.
For this reason, many are surprised when the frequency of 1200 MHz DDR is indicated for the memory of their video card, and utilities report 600 MHz. So you'll have to get used to it. DDR2 and GDDR3/GDDR4 memory works on the same principle, that is, with double data transfer. The difference between DDR, DDR2, GDDR3 and GDDR4 memory lies in production technology and some details. DDR2 can operate at higher frequencies than DDR memory, and DDR3 can operate at even higher frequencies than DDR2.
Memory bus frequency
Like a processor, memory (or more precisely, the memory bus) operates at specific clock speeds, measured in megahertz. Here, increasing clock speeds directly affects memory performance. And the memory bus frequency is one of the parameters that is used to compare the performance of video cards. For example, if all other characteristics (memory bus width, etc.) are the same, then it is quite logical to say that a video card with 700 MHz memory is faster than one with 500 MHz memory.
Again, clock speed isn't everything. 700 MHz memory with a 64-bit bus will be slower than 400 MHz memory with a 128-bit bus. The performance of 400 MHz memory on a 128-bit bus is approximately equivalent to 800 MHz memory on a 64-bit bus. You should also remember that GPU and memory frequencies are completely different parameters, and they usually differ.
Video card interface
All data transferred between the video card and the processor passes through the video card interface. Today, three types of interfaces are used for video cards: PCI, AGP and PCI Express. They differ in bandwidth and other characteristics. It is clear that the higher the throughput, the higher the exchange speed. However, only the most modern cards can use high bandwidth, and even then only partially. At some point, interface speed ceased to be a bottleneck; today it is simply sufficient.
The slowest bus for which video cards were produced is PCI (Peripheral Components Interconnect). Without going into history, of course. PCI really degraded the performance of video cards, so they switched to the AGP (Accelerated Graphics Port) interface. But even the AGP 1.0 and 2x specifications limited performance. When the standard increased speeds to AGP 4x levels, we began to approach the practical limit of the bandwidth that video cards can handle. The AGP 8x specification once again doubled the throughput compared to AGP 4x (2.16 GB/s), but we no longer received a noticeable increase in graphics performance.
The newest and fastest bus is PCI Express. New graphics cards typically use the PCI Express x16 interface, which combines 16 PCI Express lanes for a total throughput of 4 GB/s (one direction). This is twice the throughput of AGP 8x. The PCI Express bus provides the mentioned bandwidth in both directions (data transfer to and from the video card). But the speed of the AGP 8x standard was already sufficient, so we have not yet encountered a situation where switching to PCI Express gave a performance increase compared to AGP 8x (if other hardware parameters are the same). For example, the AGP version of the GeForce 6800 Ultra will work identically to the 6800 Ultra for PCI Express.
Today it is best to buy a card with a PCI Express interface; it will remain on the market for several more years. The most powerful cards are no longer produced with the AGP 8x interface, and PCI Express solutions, as a rule, are easier to find than AGP analogues, and they are cheaper.
Solutions on multiple video cards
Using multiple video cards to increase graphics performance is not a new idea. In the early days of 3D graphics, 3dfx entered the market with two graphics cards running in parallel. But with the disappearance of 3dfx, the technology for joint operation of several consumer video cards was consigned to oblivion, although ATi had been producing similar systems for professional simulators since the release of the Radeon 9700. A couple of years ago, the technology returned to the market: with the advent of nVidia SLI solutions and, a little later, ATi Crossfire.
Using multiple graphics cards together provides enough performance to run the game at high quality settings in high resolution. But choosing one solution or another is not so simple.
Let's start with the fact that solutions based on multiple video cards require a large amount of energy, so the power supply must be powerful enough. All this heat will have to be removed from the video card, so you need to pay attention to the PC case and cooling so that the system does not overheat.
Also, remember that SLI/CrossFire requires the appropriate motherboard(either for one technology or another), which usually costs more compared to standard models. The nVidia SLI configuration will only work on certain nForce4 boards, and ATi CrossFire cards will only work on motherboards with the CrossFire chipset or on certain Intel models. To complicate matters, some CrossFire configurations require one of the cards to be a special one: CrossFire Edition. After the release of CrossFire, for some models of video cards, ATi allowed the inclusion of collaboration technology via the PCI Express bus, and with the release of new driver versions, the number of possible combinations increases. But still, hardware CrossFire with the corresponding CrossFire Edition card provides higher performance. But CrossFire Edition cards are also more expensive than regular models. For now, you can enable CrossFire software mode (without a CrossFire Edition card) on Radeon video cards X1300, X1600 and X1800 GTO.
There are other factors to consider as well. Although two graphics cards working together provide a performance boost, it is far from double. But you will pay twice as much money. Most often, the productivity increase is 20-60%. And in some cases, due to additional computational costs for matching, there is no increase at all. For this reason, multi-card configurations are unlikely to be worthwhile with cheaper models, since the more expensive graphics card will usually always outperform a couple of cheaper cards. In general, for most consumers, purchasing an SLI/CrossFire solution does not make sense. But if you want to enable all the quality enhancement options or play at extreme resolutions, for example, 2560x1600, when you need to calculate more than 4 million pixels per frame, then you can’t do without two or four paired video cards.
Visual features
In addition to purely hardware specifications, different generations and models of GPUs may differ in the set of functions. For example, it is often said that the ATi Radeon X800 XT generation cards are compatible with Shader Model 2.0b (SM), while the nVidia GeForce 6800 Ultra is compatible with SM 3.0, although their hardware specifications are close to each other (16 pipelines). Therefore, many consumers make a choice in favor of one solution or another without even knowing what the difference means.
Microsoft DirectX and Shader Model versions
These names are most often used in disputes, but few people know what they really mean. To understand, let's start with the history of graphics APIs. DirectX and OpenGL are graphics APIs, that is, Application Programming Interfaces - open code standards available to everyone.
Before the advent of graphics APIs, each GPU manufacturer used its own mechanism to communicate with games. Developers had to write separate code for each GPU they wanted to support. A very expensive and ineffective approach. To solve this problem, APIs for 3D graphics were developed so that developers write code for a specific API, and not for a particular video card. After that, compatibility problems fell on the shoulders of video card manufacturers, who had to ensure that the drivers would be compatible with the API.
The only difficulty remains that today two different APIs are used, namely Microsoft DirectX and OpenGL, where GL stands for Graphics Library. Since the DirectX API is more popular in games today, we will focus on it. And this standard had a stronger influence on the development of games.
DirectX is a Microsoft creation. In fact, DirectX includes several APIs, only one of which is used for 3D graphics. DirectX includes APIs for sound, music, input devices, etc. The Direct3D API is responsible for 3D graphics in DirectX. When they talk about video cards, this is what they mean, so in this regard the concepts DirectX and Direct3D are interchangeable.
DirectX is updated periodically as graphics technology advances and game developers implement new game programming techniques. As DirectX quickly grew in popularity, GPU manufacturers began tailoring new product releases to accommodate DirectX capabilities. For this reason, video cards are often tied to hardware support for one or another generation of DirectX (DirectX 8, 9.0 or 9.0c).
To complicate matters, parts of the Direct3D API can change over time without changing DirectX generations. For example, the DirectX 9.0 specification specifies support for Pixel Shader 2.0. But the DirectX 9.0c update includes Pixel Shader 3.0. So, although the cards are DirectX 9-class, they can support different feature sets. For example, the Radeon 9700 supports Shader Model 2.0, and the Radeon X1800 supports Shader Model 3.0, although both cards can be classified as DirectX 9 generation.
Remember that when creating new games, developers take into account the owners of old machines and video cards, since if you ignore this segment of users, the level of sales will be lower. For this reason, multiple code paths are built into games. A DirectX 9 class game probably has a DirectX 8 path and even a DirectX 7 path for compatibility. Usually, if the old path is selected, then some of the virtual effects that are present on new video cards disappear from the game. But at least you can play even on old hardware.
Many new games require the latest version of DirectX to be installed, even if the video card is from a previous generation. That is, a new game that will use the DirectX 8 path will still require installing the latest version of DirectX 9 for a DirectX 8 class video card.
What are the differences between different versions of the Direct3D API in DirectX? Early versions of DirectX - 3, 5, 6 and 7 - were relatively simple in the capabilities of the Direct3D API. Developers could choose visual effects from the list, and then check their operation in the game. The next major step in graphics programming was DirectX 8. It introduced the ability to program the video card using shaders, so developers for the first time had the freedom to program effects the way they needed. DirectX 8 supported versions of Pixel Shader 1.0 to 1.3 and Vertex Shader 1.0. DirectX 8.1, an updated version of DirectX 8, received Pixel Shader 1.4 and Vertex Shader 1.1.
In DirectX 9 you can create even more complex shader programs. DirectX 9 supports Pixel Shader 2.0 and Vertex Shader 2.0. DirectX 9c, an updated version of DirectX 9, included the Pixel Shader 3.0 specification.
DirectX 10, the upcoming API version, will accompany new version Windows Vista. You cannot install DirectX 10 on Windows XP.
HDR lighting and OpenEXR HDR
HDR stands for “High Dynamic Range”. A game with HDR lighting can produce a much more realistic image than a game without it, and not all video cards support HDR lighting.
Before the advent of DirectX 9 graphics cards, GPUs were severely limited by the accuracy of their lighting calculations. Until now, lighting could only be calculated with 256 (8 bits) internal levels.
When DirectX 9 video cards appeared, they were able to produce lighting with high precision - full 24 bits or 16.7 million levels.
With 16.7 million levels and the next step in the performance of DirectX 9/Shader Model 2.0 video cards, HDR lighting became possible on computers. This is a rather complex technology, and you need to watch it in dynamics. If we talk in simple words, then HDR lighting increases contrast (dark shades appear darker, light shades appear lighter), while increasing the amount of lighting detail in dark and light areas. The game with HDR lighting seems more vibrant and realistic than without it.
GPUs compliant with the latest Pixel Shader 3.0 specification enable higher 32-bit precision lighting calculations and floating point blending. Thus, SM 3.0 class video cards can support a special OpenEXR HDR lighting method specifically designed for the film industry.
Some games that only support OpenEXR HDR lighting will not run with HDR lighting on Shader Model 2.0 graphics cards. However, games that do not rely on the OpenEXR method will run on any DirectX 9 graphics card. For example, Oblivion uses the OpenEXR HDR method and only allows HDR lighting on the latest graphics cards that support the Shader Model 3.0 specification. For example, nVidia GeForce 6800 or ATi Radeon X1800. Games that use Half-Life 2's 3D engine, including Counter-Strike: Source and the upcoming Half-Life 2: Aftermath, allow HDR rendering to be enabled on older DirectX 9 graphics cards that only support Pixel Shader 2.0. Examples include the GeForce 5 or ATi Radeon 9500 line.
Finally, keep in mind that all forms of HDR rendering require serious processing power and can bring even the most powerful GPUs to their knees. If you want to play the latest games with HDR lighting, high-performance graphics are a must.
Full screen anti-aliasing
Full screen anti-aliasing (AA for short) allows you to eliminate the characteristic “ladders” at the boundaries of polygons. But it should be taken into account that full-screen anti-aliasing consumes a lot of computing resources, which leads to a drop in frame rates.
Anti-aliasing is very dependent on video memory performance, so a high-speed video card with fast memory will be able to calculate full-screen anti-aliasing with less impact on performance than an inexpensive video card. Antialiasing can be enabled in various modes. For example, 4x antialiasing will produce a better image than 2x antialiasing, but it will be a big hit to performance. While 2x antialiasing doubles horizontal and vertical resolution, 4x mode quadruples it.
Texture filtering
Textures are applied to all 3D objects in the game, and the larger the angle of the displayed surface, the more distorted the texture will look. To eliminate this effect, GPUs use texture filtering.
The first filtering method was called bilinear and produced characteristic stripes that were not very pleasing to the eye. The situation improved with the introduction of trilinear filtering. Both options work on modern video cards with virtually no performance penalty.
Today's most the best way Texture filtering is anisotropic filtering (AF). Like full-screen antialiasing, anisotropic filtering can be enabled at different levels. For example, 8x AF gives more high quality filtering than 4x AF. Like full screen antialiasing, anisotropic filtering requires a certain amount of processing power, which increases as the AF level increases.
High resolution textures
All 3D games are created with specific specifications in mind, and one of those requirements determines the texture memory that the game will need. All the necessary textures must fit into the video card's memory during the game, otherwise performance will drop significantly, since accessing the texture to the RAM causes a considerable delay, not to mention the paging file on the hard drive. Therefore, if a game developer is counting on 128 MB of video memory as minimum requirement, then the set of active textures should not exceed 128 MB at any time.
Modern games have several sets of textures, so the game will run without problems on older video cards with less video memory, as well as on new cards with more video memory. For example, a game may contain three sets of textures: for 128 MB, 256 MB and 512 MB. There are very few games today that support 512 MB of video memory, but they are still the most objective reason to buy a video card with this amount of memory. While the increase in memory has little to no impact on performance, you will benefit from improved visual quality if the game supports the appropriate set of textures.
What you need to know about video cards?
In contact with
Unified shader units combine the two types of units listed above; they can execute both vertex and pixel programs (as well as geometric ones, which appeared in DirectX 10). The unification of shader blocks means that the code of different shader programs (vertex, pixel and geometry) is universal, and the corresponding unified processors can execute any of the above programs. Accordingly, in new architectures the number of pixel, vertex and geometry shader units seems to merge into one number - the number of universal processors.
Texturing units (tmu)
These blocks work in conjunction with shader processors of all specified types; they select and filter the texture data necessary for constructing the scene. The number of texture units in the video chip determines the texture performance, the speed of sampling from textures. And although recently most of the calculations are carried out by shader units, the load on TMUs is still quite high, and given the emphasis of some applications on the performance of texturing units, we can say that the number of TMUs and the corresponding high texture performance is one of the most important parameters video chips. This parameter has a particular impact on the speed when using trilinear and anisotropic filtering, which require additional texture samples.
Rasterization operation blocks (rop)
Rasterization units carry out the operations of writing pixels calculated by the video card into buffers and the operations of mixing them (blending). As noted above, the performance of ROP blocks affects the fill rate and this is one of the main characteristics of video cards. And although its importance has decreased somewhat recently, there are still cases where application performance is highly dependent on the speed and number of ROP blocks. Most often this is due to the active use of post-processing filters and anti-aliasing enabled at high image settings.
Video memory capacity
Own memory is used by video chips to store the necessary data: textures, vertices, buffers, etc. It would seem that the more there is, the better. But it’s not so simple; estimating the power of a video card based on the amount of video memory is the most common mistake! Inexperienced users most often overestimate the value of memory, using it to compare different models of video cards. This is understandable - since the parameter, one of the first indicated in all sources, is twice as large, then the speed of the solution should be twice as high, they believe. The reality differs from this myth in that productivity growth grows up to a certain volume and, after reaching it, simply stops.
Each application has a certain amount of video memory, which is enough for all data, and even if you put 4 GB there, there will be no reason for it to speed up rendering, the speed will be limited by the execution units. This is why, in almost all cases, a video card with 320 MB of video memory will work at the same speed as a card with 640 MB (all other things being equal). There are situations where more memory leads to a visible increase in performance, these are very demanding applications at high resolutions and at maximum settings. But such cases are very rare, therefore, the amount of memory of course needs to be taken into account, but not forgetting that performance simply does not increase above a certain amount, there are more important parameters, such as the width of the memory bus and its operating frequency.
On our forum every day, dozens of people ask for advice on modernizing their machines, with which we willingly help them. Every day, “evaluating the assembly” and checking the components chosen by our clients for compatibility, we began to notice that users mainly pay attention to other, undoubtedly important components. And rarely does anyone remember that when upgrading a computer, it is necessary to update an equally important part -. And today we will tell and show why you should not forget about this.
“...I want to upgrade my computer so that everything is flying, I bought an i7-3970X and an ASRock X79 Extreme6 motherboard, plus a RADEON HD 7990 6GB video card. What else is nan????777"
- this is how about half of all messages regarding the update begin desktop computer. Based on their or family budget, users try to choose the fastest, fastest and most beautiful memory modules. At the same time, naively believing that their old 450W one will cope with both a power-hungry video card and a “hot” processor during overclocking at the same time.
We, for our part, have already written more than once about the importance of the power supply - but, we confess, it was probably not clear enough. Therefore, today we have corrected ourselves and have prepared for you a reminder about what will happen if you forget about it when upgrading your PC - with pictures and detailed descriptions.
So, we decided to update the configuration...
For our experiment, we decided to take a completely new average computer and upgrade it to the “gaming machine” level. There is no need to change the configuration much - it will be enough to change the memory and video card so that we have the opportunity to play more or less modern games with decent detail settings. The initial configuration of our computer is as follows:
Power unit: ATX 12V 400W
It is clear that for games this configuration is, to put it mildly, rather weak. So it's time to change something! We’ll start with the same thing where most of those hungry for an “upgrade” start - with. We will not change the motherboard - as long as it suits us.
Since we decided not to touch the motherboard, we will select one that is compatible with the FM2 socket (fortunately, there is a special button for this on the NICS website on the motherboard description page). Let's not be greedy - let's take an affordable, but fast and powerful processor with a frequency of 4.1 GHz (up to 4.4 GHz in Turbo CORE mode) and an unlocked multiplier - we also love to overclock, nothing human is alien to us. Here are the characteristics of the processor we chose:
| Characteristics | CPU bus frequency | 5000 MHz | Power dissipation | 100 W | Processor frequency | 4.1 GHz or up to 4.4 GHz in Turbo CORE mode | Core | Richland | L1 cache | 96 KB x2 | L2 cache | 2048 KB x2, running at processor speed | 64 bit support | Yes | Number of Cores | 4 | Multiplication | 41, unlocked multiplier | Processor video core | AMD Radeon HD 8670D with a frequency of 844 MHz; Shader Model 5 support | Max volume random access memory | 64 GB | Max. number of connected monitors | 3 directly connected or up to 4 monitors using DisplayPort splitters |
One 4GB stick is not our choice. Firstly, we want 16GB, and secondly, we need to use dual-channel operating mode, for which we will install two memory modules of 8GB each in our computer. High throughput, lack of radiators and a decent price make these the most “delicious” choice for us. In addition, from the AMD website you can download the Radeon RAMDisk program, which will allow us to create a super-fast virtual drive up to 6GB absolutely free of charge - and everyone loves free useful things.
| Characteristics | |
| Memory | 8 GB |
| Number of modules | 2 |
| Memory standard | PC3-10600 (DDR3 1333 MHz) |
| Operating frequency | up to 1333 MHz |
| Timings | 9-9-9-24 |
| Supply voltage | 1.5 V |
| Bandwidth | 10667 Mb/sec |
You can play comfortably on the built-in video only in “minesweeper”. Therefore, in order to upgrade your computer to a gaming level, we chose a modern and powerful, but not the most expensive, .
It came with 2GB of video memory, support for DirectX 11 and OpenGL 4.x. and an excellent Twin Frozr IV cooling system. Its performance should be more than enough for us to enjoy the latest installments of the most popular gaming franchises, such as Tomb Raider, Crysis, Hitman and Far Cry. The characteristics of the one we have chosen are as follows:
| Characteristics | |
| GPU | GeForce GTX 770 |
| GPU frequency | 1098 MHz or up to 1150 MHz in GPU Boost mode |
| Number of shader processors | 1536 |
| Video memory | 2 GB |
| Video memory type | GDDR5 |
| Video memory bus width | 256 bit |
| Video memory frequency | 1753 MHz (7.010 GHz QDR) |
| Number of pixel pipelines | 128, 32 texture sampling units |
| Interface | PCI Express 3.0 16x (compatible with PCI Express 2.x/1.x) with the ability to combine cards using SLI. |
| Ports | DisplayPort, DVI-D, DVI-I, HDMI, D-Sub adapter included |
| Cooling the video card | Active (heatsink + 2 Twin Frozr IV fans on the front side of the board) |
| Power connector | 8 pin+8 pin |
| API support | DirectX 11 and OpenGL 4.x |
| Video card length (measured in NICS) | 263 mm |
| Support for general purpose GPU computing | DirectCompute 11, NVIDIA PhysX, CUDA, CUDA C++, OpenCL 1.0 |
| Maximum power consumption FurMark+WinRar | 255 W |
| Performance Rating | 61.5 |
Unexpected difficulties
Now we have everything we need to upgrade our computer. We will install new components into our existing case.
We launch it and it doesn’t work. And why? But because budget power supplies are physically not capable of running a computer with any power. The fact is that in our case, power supply requires two 8-pin connectors, and the power supply has only one 6-pin video card power connector in its base. Considering that many people need even more connectors than in our case, it becomes clear that the power supply needs to be changed.
But that's not so bad. Just think, there is no power connector! In our test laboratory we found quite rare adapters from 6-pin to 8-pin and from molex to 6-pin. Like these ones:
It is worth noting that even on budget modern power supplies, with each new release of Molex connectors there are fewer and fewer Molex connectors - so we can say that we are lucky.
At first glance, everything is fine, and with some tricks we were able to update system unit to the “gamer” configuration. Now let's simulate the load by running the Furmark test and the 7Zip archiver in Xtreme Burning mode simultaneously on our new gaming computer. We could start the computer - already good. The system also survived the launch of Furmark. We launch the archiver - and what is it?! The computer turned off, delighting us with the roar of a fan turned up to maximum. The “modest” standard 400W was unable, no matter how hard he tried, to feed the video card and powerful processor. And due to the mediocre cooling system, ours got very hot, and even the maximum fan speed did not allow it to produce at least the declared 400W.
There is an exit!
We've arrived. We bought expensive components to assemble a gaming computer, but it turns out we can’t play on it. It's a shame. The conclusion is clear to everyone: the old one is not suitable for our gaming computer, and it urgently needs to be replaced with a new one. But which one exactly?
For our upgraded computer, we chose according to four main criteria:
The first is, of course, power. We preferred to choose with a reserve - we would want to overclock the processor and gain points in synthetic tests. Taking into account everything that we may need in the future, we decided to choose a power of at least 800W.
The second criterion is reliability. We really want the one taken “with reserve” to survive the next generation of video cards and processors, not burn out on its own, and at the same time not burn expensive components (along with the test platform). Therefore, our choice is only Japanese capacitors, only short circuit protection and reliable overload protection of any of the outputs.
The third point of our requirements is convenience and functionality.. To begin with, we need - the computer will work often, and especially noisy power supplies, coupled with a video card and processor cooler, will drive any user crazy. In addition, we are not alien to the feeling of beauty, therefore new block The power supply for our gaming computer should be modular and have detachable cables and connectors. So that there is nothing superfluous.
And last on the list, but not least, the criterion is energy efficiency. Yes, we care and environment, and electricity bills. Therefore, the power supply we choose must meet at least the 80+ Bronze energy efficiency standard.
Having compared and analyzed all the requirements, we chose, among the few applicants, the one that most fully satisfied all our requirements. It became a power of 850W. Note that in a number of parameters it even exceeded our requirements. Let's see its specification:
| Power supply characteristics | |
| Type of equipment | Power supply with active PFC (Power Factor Correction) module. |
| Properties | Loop braiding, Japanese capacitors, Short circuit protection (SCP), Overvoltage protection (OVP), Overload protection of any of the unit outputs individually (OCP) |
| +3.3V - 24A, +5V - 24A, +12V - 70A, +5VSB - 3.0A, -12V - 0.5 A | |
| Detachable power cables | Yes |
| Efficiency | 90%, 80 PLUS Gold certified |
| Power supply power | 850 W |
| Motherboard power connector | 24+8+8 pin, 24+8+4 pin, 24+8 pin, 24+4 pin, 20+4 pin (detachable 24-pin connector. 4-pin can be detached if necessary, detachable 8-pin connector) |
| Video card power connector | 6x 6/8-pin connectors (dismountable 8-pin connector - 2 pins detachable) |
| MTBF | 100 thousand hours |
| Cooling the power supply | 1 fan: 140 x 140 mm (on the bottom wall). Passive cooling system at load up to 50%. |
| Fan speed control | From the temperature sensor. Changing the fan speed depending on the temperature inside the power supply. Manual selection of fan operating mode. In Normal mode, the fan rotates constantly, and in Silent mode it stops completely at low load. |
, one of the best for the money. Let's install it in our case:
Then something happened that confused us a little. It would seem that everything was assembled correctly, everything was connected, everything worked - but the power supply is silent! That is, in general: the fan has been standing still and is still standing, and the system has started up properly and is functioning. The fact is that at a load of up to 50%, the power supply operates in the so-called quiet mode - without spinning up the cooling system fan. The fan will hum only under heavy load - simultaneous launch of archivers and Furmark still made the cooler rotate.
The power supply has as many as six 8-pin6-pin video card power connectors, each of which is a collapsible 8-pin connector, from which 2 pins can be unfastened if necessary. Thus, it is able to feed any video card without any hassle or difficulty. And not even one.
The modular power supply system allows you to unfasten excess and unnecessary power cables, which improves the airflow of the case, system stability and, of course, improves aesthetics appearance internal space, which allows us to safely recommend it to modders and fans of cases with windows.
buy a reliable and powerful power supply. In our review it became. - and as you can see, it’s no coincidence. By purchasing one from NICS, you can be sure that all components of your high-performance system will be provided with sufficient and uninterrupted power, even under extreme overclocking.
In addition, the power supply will have enough power for several years to come - it is better with a reserve in case you are going to update the system with high-level components in the future.
