Thursday, July 17, 2008

Buyers guide to graphics cards

Every PC comes with a graphics card (or adaptor) inside. Without one your computer would be unable to display anything on your monitor. Your system may have a dedicated card or, if it is of a lower specification, its graphics capability might be built-in to your motherboard. If you only use your computer for browsing the web, email and word processing, your current set-up will probably be fine. If, however, you want to use it for more visually demanding tasks such as video editing or playing 3D games, it may be worth considering an upgrade.

What does a graphics card do?
The role of a dedicated graphics card is to take processor-intensive tasks – such as moving polygons around the screen, calculating lighting, shading and rendering 3D objects – away from your PC’s main processor, leaving it free for other tasks. A graphics card works like a mini-computer within your PC, so the more memory it has and the more powerful its central processing chip, the faster it will be.

Do I need to upgrade?
If your computer is running slowly, buying a new graphics card won’t speed things up significantly – you’d be better off upgrading your memory as a starter, then maybe your motherboard or computer’s main processor. If on the other hand graphics performance is the one thing that is letting your system down, adding a new card will definitely improve matters. It will also let you play games at a much higher screen resolution. The type of graphics card you buy should match the specification of your computer (see ‘How much to spend?’).

ATI or nVidia?
Two companies make the GPU (Graphics Processing Unit) chips that nearly all of today’s graphics cards are built around. The processor range from ATI ( is known as Radeon, while nVidia’s ( is called GeForce. These chips are used on boards from a variety of manufacturers including Gainward, Sapphire, Asus and MSI. Choosing whether to go for an ATI card or an nVidia model is largely a matter of a personal choice.

Slot types
There are two types of motherboard expansion port designed expressly for graphics cards. If your computer is new, it could well have a PCI Express (Peripheral Component Interconnect Express) slot – the fastest, most modern option. These come in different sizes with the graphics cards fitting into the long x16 slot (the purple section in the picture above). If it doesn’t support PCI Express then it will most likely have AGP (Accelerated Graphics Port) instead. Older or very basic PCs may only have straightforward PCI slots (white in the picture above). It’s important to find out which type you have, as a card designed for one port won’t fit into another.

Before buying
You should check to see what space you have inside your computer’s case. Many new cards are bulky and may not fit inside your PC if space is restricted. Also, some high-end cards need connecting to your PC’s power supply. If you don’t have a spare Molex connector (large, white, square head) you’ll need to buy a Y cable splitter/extension cable (see picture, left).

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