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What is the shader frequency in the card. Wise choice of video card

Modern graphics processors contain many functional blocks, the number and characteristics of which determine the final rendering speed, which affects the comfort of the game. By comparative amount Using these blocks in different video chips, you can roughly estimate how fast a particular GPU is. Video chips have quite a lot of characteristics; in this section we will consider only the most important of them.

Video chip clock speed

The operating frequency of a GPU is usually measured in megahertz, i.e., millions of cycles per second. This characteristic directly affects the performance of the video chip - the higher it is, the more work the GPU can perform per unit of time, process a greater number of vertices and pixels. An example from real life: the frequency of the video chip installed on the Radeon HD 6670 board is 840 MHz, and exactly the same chip in the Radeon HD 6570 model operates at a frequency of 650 MHz. Accordingly, all the main performance characteristics will differ. But it’s not only the operating frequency of the chip that determines performance; its speed is greatly influenced by the graphics architecture itself: the design and number of execution units, their characteristics, etc.

In some cases, the clock speed of individual GPU blocks differs from the operating frequency of the rest of the chip. That is, different parts of the GPU operate at different frequencies, and this is done to increase efficiency, because some blocks are capable of operating at higher frequencies, while others are not. Most GeForce video cards from NVIDIA are equipped with these GPUs. As a recent example, let's look at the video chip in the GTX 580 model, most of which operates at a frequency of 772 MHz, and the universal computing units of the chip have a frequency doubled - 1544 MHz.

Fill rate

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 peak pixel fillrate of the GeForce GTX 560 Ti is 822 (chip frequency) × 32 (number of ROP units) = 26304 megapixels per second, and the texture fillrate is 822 × 64 (number of texturing units) = 52608 megatexels/s. In a simplified way, the situation is like this - 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.

Although the importance of "pure" fill rate has recently decreased markedly, giving way to computational speed, these parameters are still very important, especially for games with simple geometry and relatively simple pixel and vertex calculations. So both parameters remain important for modern games, but they must be balanced. Therefore, the number of ROP units in modern video chips is usually less than the number of texture units.

Number of computing (shader) units or processors

Perhaps, now these blocks are the main parts of the video chip. They run special programs known as shaders. Moreover, if earlier pixel shaders performed pixel shader blocks, and vertex shaders performed vertex blocks, then for some time graphic architectures were unified, and these universal computing units began to deal with various calculations: vertex, pixel, geometric and even universal calculations.

For the first time, the unified architecture was used in the video chip of the Microsoft Xbox 360 game console; this graphics processor was developed by ATI (later purchased by AMD). And in video chips for personal computers, unified shader units appeared in the NVIDIA GeForce 8800 board. And since then, all new video chips are based on a unified architecture, which has a universal code for different shader programs (vertex, pixel, geometric, etc.), and the corresponding Unified processors can execute any program.

Based on the number of computational units and their frequency, you can compare the mathematical performance of different video cards. Most games are now limited by the performance of pixel shaders, so the number of these blocks is very important. For example, if one video card model is based on a GPU with 384 computational processors in its composition, and another from the same line has a GPU with 192 computational units, then at the same frequency the second will be twice as slow to process any type of shaders, and in general will be the same more productive.

Although it is impossible to draw unambiguous conclusions about performance solely on the basis of the number of computing units alone, it is necessary to take into account the clock frequency and the different architecture of units of different generations and chip manufacturers. Only based on these numbers, you can compare chips only within the same line of one manufacturer: AMD or NVIDIA. In other cases, you need to pay attention to performance tests in the games or applications you are interested in.

Texturing Units (TMU)

These GPU units work in conjunction with computing processors; they select and filter texture and other data necessary for scene construction and general-purpose calculations. The number of texture units in a video chip determines texture performance—that is, the speed of fetching texels from textures.

Although recently more emphasis has been placed on mathematical calculations, and some textures are being replaced by procedural ones, the load on TMU blocks is still quite high, since in addition to the main textures, selections must also be made from normal and displacement maps, as well as off-screen render target rendering buffers.

Taking into account the emphasis of many games, including the performance of texturing units, we can say that the number of TMU units and the corresponding high texture performance are also one of the most important parameters for video chips. This parameter has a particular impact on the speed of image rendering when using anisotropic filtering, which requires additional texture samples, as well as with complex soft shadow algorithms and newfangled algorithms like Screen Space Ambient Occlusion.

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).

In this material, we will not go into details; they can be read in the basic materials on our website dedicated to DirectX 11-compatible graphics processors. What's important to us here is that the number of geometry processing units has a huge impact on overall performance in the newest games that use tessellation, like Metro 2033, HAWX 2 and Crysis 2 (with the latest patches). And when choosing a modern gaming video card, it is very important to pay attention to geometric performance.

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.

So, in each game and with certain settings and game scenes there is a certain amount of video memory that is enough for all the data. And even if you put 4 GB of video memory there, there will be no reason for it to speed up rendering, the speed will be limited by the execution units discussed above, and there will simply be enough memory. This is why, in many cases, a video card with 1.5 GB of video memory runs at the same speed as a card with 3 GB (all other things being equal).

There are situations where more memory leads to a visible increase in performance - these are very demanding games, especially at ultra-high resolutions and at maximum quality settings. But such cases do not always occur and the amount of memory must be taken into account, not forgetting that performance simply will not increase above a certain amount. Memory chips have more important parameters, such as the memory bus width and its operating frequency. This topic is so vast that we will go into more detail about choosing the amount of video memory in the sixth part of our material.

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.

Particular attention to the parameters of the memory bus width, its type and operating frequency should be paid when purchasing relatively inexpensive video cards, many of which only have 128-bit or even 64-bit interfaces, which has an extremely negative impact on their performance. In general, we do not recommend purchasing a video card using a 64-bit video memory bus for a gaming PC. It is advisable to give preference to at least a medium level with at least a 128- or 192-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 therefore increase bandwidth compared to previous technologies. This is achieved at the expense of increased latencies, which, however, are not so important for video cards. The first board to use DDR2 memory was the NVIDIA GeForce FX 5800 Ultra. Since then, graphics memory technology has advanced significantly, and the GDDR3 standard was developed, which is close to the DDR2 specifications, with some changes specifically for video cards.

GDDR3 is a memory specifically designed for video cards, with the same technologies as DDR2, but with improved consumption and heat dissipation characteristics, which made it possible to create chips that operate at higher clock speeds. Despite the fact that the standard was developed by ATI, the first video card to use it was the second modification of the NVIDIA GeForce FX 5700 Ultra, and the next one was the GeForce 6800 Ultra.

GDDR4 is a further development of “graphics” memory, running almost twice as fast as GDDR3. The main differences between GDDR4 and GDDR3, which are significant for users, are once again increased operating frequencies and reduced power consumption. Technically, GDDR4 memory is not very different from GDDR3; it is a further development of the same ideas. The first video cards with GDDR4 chips on board were ATI Radeon X1950 XTX, and NVIDIA did not release products based on this type of memory at all. The advantages of new memory chips over GDDR3 are that the power consumption of the modules can be about a third lower. This is achieved through a lower voltage rating for GDDR4.

However, GDDR4 is not widely used even in AMD solutions. Starting with the RV7x0 family of GPUs, video card memory controllers support a new type of GDDR5 memory operating at an effective quadruple frequency of up to 5.5 GHz and higher (theoretically, frequencies up to 7 GHz are possible), which gives a throughput of up to 176 GB/s using 256-bit interface. If to increase memory bandwidth in GDDR3/GDDR4 memory it was necessary to use a 512-bit bus, then switching to GDDR5 made it possible to double the performance with smaller crystal sizes and lower power consumption.

The most modern types of video memory are GDDR3 and GDDR5; they differ from DDR in some details and also work with double/quadruple data transfer. These types of memory use some special technologies to increase the operating frequency. Thus, GDDR2 memory usually operates at higher frequencies compared to DDR, GDDR3 at even higher frequencies, and GDDR5 provides maximum frequency and current capacity. But inexpensive models are still equipped with “non-graphic” DDR3 memory with a significantly lower frequency, so you need to choose a video card more carefully.

Theoretically, a modern computer can exist without a video card - it’s not for nothing that motherboards are equipped with one or even two connectors used to connect a monitor. Owners of processors with integrated graphics core. But even they buy a video card if they want to play modern games. Only a video adapter can provide a decent level of graphics. And it helps even more in case of video editing or working on visual special effects. But how to choose the right model?

Dependence of the video adapter on other components

We warn you right away that you should first of all focus on existing computer components! Imagine purchasing the most powerful NVIDIA TITAN while in your system unit houses a modest dual-core processor. It simply will not be able to process all the information that comes to it from the video card. Due to this, your TITAN will only use half or even a quarter of its capabilities.

In a word, choose components of approximately the same class. If you buy a powerful gaming video card, then the processor with motherboard shouldn't be cheap. There are no problems only with budget video adapters designed for processing office graphics. As a rule, any motherboard and processor can get the most out of such a device, unless we are talking about a ten-year-old single-core chipset.

Photo: domcomputer.ru

Main selection criteria

Connection interface

As you know, video adapters are inserted into a PCI-Express slot. It is available in almost every motherboard, with the exception of the most miniature models. But the version of this interface may differ! If you are building a computer right now, you will definitely purchase a motherboard with a slot PCI-Express 3.0. But if you are selecting a video card for your existing “mother,” then it would be a good idea to familiarize yourself with which version of the interface it uses. It's possible that this is outdated PCI-Express 2.0.

There is nothing wrong with installing a video card on a previous generation interface. You just won't be able to use all its features, since it will work in compatibility mode. The difference between the interfaces lies only in bandwidth - you can forget about the high level of graphics in modern games. This is also true in the opposite direction. Video adapters designed for PCI-Express 2.0 will also work in the new slot. But it’s better to look for a newer video card in order to unlock the potential of the motherboard.

Energy consumption

Long gone are the days when a video accelerator did not require additional power. Now only the number of connectors used to connect the power supply differs. The most powerful models require power supply via two connectors 8PIN— if your power supply does not have such cables, then you will have to worry about purchasing adapters that use MOLEX. Slightly less powerful video cards can use a single 8PIN connector or even 6PIN.

Of course, the level of power consumption differs between video adapters. IN technical specifications This usually indicates how much electricity the video card requires when idle and under load. Typically this parameter varies from 50 to 350 W. If you are not going to change the power supply, then select a video card for it. For example, the GeForce 770 with a cooling system from GIGABYTE consumes up to 220 W in games. Add to this the power consumption of your existing hard drives, CD drive, sound card and motherboard. As a result, you will get that such a video card requires a power supply of at least 600 W. If your power supply is not capable of delivering this amount of electricity, then you should consider a simpler video adapter. Or NVIDIA GeForce 970, created using a sophisticated technical process and consuming less power.

Video memory size and bus

Many people think that the more video memory a video card has, the better. However, in reality this is not always the case. The fact is that video memory is consumed through a special bus. And if its bandwidth is too low, then in a rare game you can use up the entire supply of available video memory. In particular, for a volume of 1 GB, a 128-bit bus is sufficient. And for a volume of 2-4 GB you need a 256-bit bus. For even more volume you will need an even wider tire. For different needs, video adapters with the following parameters may be required:

Office work- in this case, you may be satisfied with a simple video card, which has 512 MB of video memory on board with a not very wide bus;
Watching videos and games from previous generations— to solve such problems you will need a video card with 1 GB of video memory (GDDR5 standard is desirable) and a bus of 128 bits or more.
Modern games with medium graphics settings— it all depends on the screen resolution. Outputting images in Full HD will require 2 GB of video memory and a 256-bit bus.
Modern games with maximum settings graphs require at least 4 GB of video memory and a bus of 256 bits (the wider, the faster the graphics will load).
Groundwork for the future and professional video editing— you will need a model equipped with 6 GB of video memory (or better yet, even more) and the widest possible bus. If high power consumption is not a concern, then you can consider a dual-processor video card or a combination of two video adapters.

Photo: bws.ucoz.ru

Video memory and processor frequency

Any video card consists of a processor and video memory. Both of these components are characterized by frequency - in this regard they are no different from the processor and random access memory, connected to the motherboard - only the numbers are completely different. In particular, video memory frequency usually increased to several thousand MHz - this is done to ensure that data exchange occurs as quickly as possible. Well, as for processor, then its clock frequency varies from 600 to 1300 MHz. The higher all these parameters are, the more high level The video adapter is capable of providing graphics.

Please note that modern video cards, the cost of which starts from 15 thousand rubles, can be overclocked! In the BIOS you can try to increase the processor frequency, achieving a slightly more interesting result.

Number of universal processors

This is also a very interesting parameter. For gamers, it is not so important, since universal processors are not always used in games. They are primarily designed to process video streams rather than 3D graphics. In particular, they are used to render video and convert one format to another. The more processors there are, the faster this process will end. For top-end video cards, the number of universal processors can reach a couple of thousand. IN budget models Only 300-500 of them can be built in. By the way, NVIDIA called this technology CUDA - you must have already heard about it.

NVIDIA Experience

Since we're talking about NVIDIA video cards, it's worth talking about their main advantage. When you install such a device, you get a program at your disposal NVIDIA Experience. Initially, it was intended only for automatically updating drivers and optimizing existing games. But now this application has a more interesting item - NVIDIA ShadowPlay. If you enable it, the video card will record your gameplay in the background (from the last five to twenty minutes). Pressing a specific key combination allows you to save the video to your hard drive.

It should be noted that this function is available only to owners of NVIDIA GeForce 600 series and higher video cards. Its main difference from Fraps, Bandicam and other similar programs is the absence of any additional load on the system, and therefore the FPS (frame rate) in games does not drop.

Photo: www.overclockers.ru

Connectors

Different connectors can be used to output images to a monitor or projector. Typically, a video card is equipped with at least four interfaces, and in expensive models you can find four or even five connectors.

HDMI- a modern digital interface, which is found in the vast majority of televisions and many monitors, the cost of which exceeds 6 thousand rubles. Please note that there are smaller versions of the connector that require the appropriate cable! Depending on the interface version, the video card can display an image on the monitor with different resolutions (up to 4K) and even in 3D form. Image output paired with sound is available.
DisplayPort- another modern connector. This interface allows you to display an image in any resolution that the video adapter supports. Along with the image, you can also output sound. The function of connecting multiple monitors is also available.
DVI- the most reliable connector. The “plug” is not only connected to it, but also screwed in with two bolts. The only drawback can be considered the resolution - the picture can be displayed in Full HD, but nothing more.
VGA- an outdated connector through which it is impossible to display an image in high resolution, and it does not support sound at all. However, many monitors still have this connection interface.

What to focus on?

If you need to display images on multiple monitors, you need to consider a powerful video card equipped with modern connectors (you should definitely forget about VGA).
Office workers will be satisfied with almost any video adapter currently sold in stores. When buying a used device, you should focus on the amount of video memory - with 512 MB, any applications related to graphics or video will work stably.
Game lovers must look for a video card with a decent video memory bus width. 256 bit is the optimal parameter, allowing games to easily use any amount of video memory - up to 4 GB.
If you love recording your gameplay or streaming, then focus on NVIDIA products - ShadowPlay will help you with this matter. But don’t forget to stock up on roomy ones before doing so. hard drive, whose choice is dedicated!

Be that as it may, when choosing a video card, you should definitely read reviews and testimonials. This is the only way to understand whether the device’s throttles are squeaking, how loud the cooling system is, and what the performance of the video adapter is in your favorite games.

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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.

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