A video card (video adapter, graphics accelerator card, display adapter, graphics card) is a device turning the images contained in the PC’s memory into output video signal received by the PC screen.

The video card is a very important component of the PC. Its sends the output image to your screen. The better the video card is, the faster that outputting and the higher the quality of the image would be (in games, in particular). Thus, if you look forward to doing something bigger than reading email and working with Microsoft Word, then you should better avoid saving money on the video adapter.

Let’s start with graphics solutions integrated into the motherboard. Such solutions are recommended only for office computers (intended for office applications, Internet), computers intended for playing music and video as well as for processing audio and video files – but not intended for gaming. It is mostly due to relatively low productivity of integrated graphics solutions. Moreover, such video cards use quite some RAM (because they don’t have their own memory modules) and cause additional loading of CPU.

Now let’s take a closer look at dedicated (separate) video adapters.

At the moment there are two video card manufacturers in the market – NVIDIA and ATI/AMD. It should be said that these companies don’t sell video cards themselves – this is done by their partners (such as ASUS, Gigabyte, MSI, etc.).

Short info about bus types  

Back in early 2000s video cards used AGP bus for connection with motherboard.

AGP (Accelerated Graphics Port) – special 32-bit video card bus developed in 1997 by Intel.

It was followed by a new, more productive bus – PCI Express.

PCI Express is an up-to-date PC bus using PCI bus software model and highly productive physical protocol based on serial binary data interchange.

It should be noted that video cards don’t have backward compatibility with buses. In other words, a PCI-E can’t be inserted into an old AGP bus and vice versa.

A person choosing a graphics adapter should pay attention to the following:

1. Graphics processing unit (GPU, visual processing unit, VPU)*. The higher the series index, the more developed the card is and the more new graphics technologies are supported by it. It should be noted, however, that the productivity doesn’t depend on the GPU series directly.  

* Graphics processing unit (GPU) – a separate device in a PC that processes graphic data. Due to up-to-date pipelined architecture today’s GPUs handle the task of graphic data processing way more effectively than CPUs do.

GPUs in up-to-date video adapters are used as 3D graphics accelerators too. Their main features (as compared to CPUs) are the following:

1) Architecture aimed at reaching maximum speed of texture, physical effect and complex graphic object processing.

2) A limited selection of commands.

2. Graphics memory size and frequency*. It seems to be all clear from the first sight – the more memory, the better. However, this statement is not always correct. For example, there is no sense in buying a video card with a weak GPU but with large graphics memory size. Besides, you should also pay attention to effective graphics memory frequency when choosing a video card – the higher the showing, the “faster” the video card memory is.

* Graphics memory – the memory used for storage of output images. There are several types of this memory.

3. Graphics memory type. Today’s budget video cards still use GDDR2 and GDDR3 memory while more expensive solutions are already based on highly efficient GDDR5. Of course, all gaming video cards are based on GDDR5 memory.

4. Memory bus width. Measured in bits. Ranges between 128 and 512 bits in up-to-date video cards. The higher this showing, the wider the video card’s memory is. This parameter is very important in the overall productivity of a video adapter. Please, note that GDDR5 memory is more productive than GDDR3 and, of course, than GDDR2. Thus, for instance, GDDR5 with 128-bit bus has got higher bandwidth than 256-bit GDDR3.

5. SLI* (NVIDIA) or CrossFireX* (ATI/AMD) support. If you plan to power up your PC with 2 or more video cards in SLI or CrossFireX mode, then you should check if the video cards you are purchasing support this mode or not. At the moment, there are no up-to-date video cards that do not support either of the abovementioned modes.

* SLI (Scalable Link Interface) – the technology allowing the use of several video cards for processing of 3D image. Developed and used by NVIDIA company.

If you want to build an up-to-date SLI-system, you will need the following components (in addition to the basic ones):

1) A motherboard with two or more PCI Express х16/2.0/2.1 slots supporting SLI technology (with NVIDIA, Intel X58, P55, P67 chipset (not all motherboards are appropriate!).

2) Advanced power supply unit.

3) GeForce GT200/GT400/GT500 series video cards with PCI Express interface.

4) Connector for video cards (usually sold together with video adapters).

Video cards should belong to one series. In other words, they should have identical chips (you won’t be able to connect GeForce GTX 460 and GTX 470 video cards in SLI). They don’t have to be produced by the same manufacturer though.

SLI GPU connection can be performed by two means:

1) With the help of a special physical connector (preferred)

2) With the help of special software

The second means increases PCI Express bus loading, which affects the productivity of a graphics processing system in a negative way.

Quad SLI, 3-Way SLI and 4-Way SLI systems are there on the market too. The first of these three unites two dual-core GPUs in an SLI system. Thus, the 3D image is processed by 4 chips. The second system type unites 3 single-core GPUs and the third – 4 single-core GPUs, consequently.

* CrossFireХ – the technology allowing simultaneous use of two or more Radeon video cards for processing of 3D image. Developed and used by ATI/AMD company.

A CrossFireХ-based system requires:

1) A motherboard with two or more PCI Express х16/2.0/2.1 slots with AMD or Intel chipset (make sure that the motherboard supports CrossFireX mode).

2) Advanced power supply unit.

3) 2 or more video cards supporting CrossFireХ.

The video cards should belong to the same series though using cards of the same model is not a must (the cards may have different chips). The productivity of a CrossFireХ system is defined by the specs of the least productive video adapter’s core.

There are two ways of building a CrossFireХ system:

1) Use of a special flexible connector (similar to SLI connector).

2) Use of special software – the video cards are not connected physically with the data being transferred via PCI Express bus. The video cards are connected by software means, with the help of drivers. The use of this means, however, results in a 10-15% decrease in productivity as compared to the previous one.

CrossFireХ mode is supported by most up-to-date motherboards with two and more PCI Express х16/2.0/2.1 video card slots (except NVIDIA chipset boards).

6. Power supply unit requirements. When purchasing a video card, pay special attention to its power requirements. In order for the graphics accelerator to function properly, the PC’s power supply unit has to produce enough power to match the requirements set in video card’s description. It will be much better if your power supply unit is capable of exceeding the required power production levels.

7. Cooling system structure. Video cards may be equipped with passive cooling (only with cooling tubes) or active cooling (with 1 or more fans being used). Coolers can be single-slot (the cooler occupies the space within one video card slot) or dual-slot (the cooler occupies a slot next to the video card). In order to avoid overheating, video cards with passive coolers (budget models) should only be installed into PC cases with enhanced cooling systems.