Graphics cards: more to consider
When multiple cards are used, their design becomes an issue. All cards need to fit alongside each other on the motherboard, without blocking another's fan or heatsink.
Graphics cards generate a huge amount of heat, and this needs to be effectively extracted. A side issue is that the noise generated during cooling can detract from your enjoyment of a game or a film.
The way a card connects to the motherboard - either via a 6- or 8-pin connector - is also important. You may need to buy an adaptor if they are incompatible.
Most high-end cards are able to render realistic 3D scenes, but you only need the 3D features if you're keen to enjoy immersive gaming environments or want to work with illustration and graphics packages.
Nonetheless, many firms are pushing the benefits of 3D graphics. nVidia has designed a 3D Vision card and the glasses necessary for stereoscopic viewing, while a number of manufacturers, including Samsung, Viewsonic and LG, showed off screens able to reproduce 3D imagery at this year's Consumer Electronics Show. We expect PC monitors and graphics cards based around the nVidia 3D Vision to debut shortly.
Aside from price, compatibility and dedicated memory, the key factor in choosing a graphics card for most users will relate to the framerates that it produces, and the number of pixels it can process per second. In order to simulate motion, the onscreen image must be redrawn so quickly that the process is imperceptible to the human eye. Anything above 24fps should be sufficient to emulate motion; most consumer camcorders record video at 30fps. Ideally, you'll want your graphics card to be able to manage similar rates.
In practice, even some of the pricier cards we've reviewed here struggled on the most demanding games. Just because a card has an impressive specification list, it doesn't mean that its performance will live up to those claims. We've stretched each card to its limits to find out just what it can deliver. For more general video playback and editing and less demanding games, all the cards we've reviewed here will be fine.
Graphics cards can be pretty demanding on other components within your machine, so pay particular attention to just how fast a (dual-core) machine you'll need to run it, as well as the minimum RAM allocation. If you're running Windows Vista, DirectX 10.0 support will be an advantage.
When choosing between graphics cards, features such as lighting and shade engines and other descriptive terms sound impressive, but are actually standard elements on any modern-day card. Likewise, anisotropic filtering and anti-aliasing will improve the overall image but, for performance purposes, a more critical issue is the number of pixel pipelines the card has. The latter has a direct correlation with the card's efficiency and ability to simultaneously redraw detail.
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