Manufacturer & Feature Set
Once you have found a model that suits you, the time has come to choose the right cardmaker. As we mentioned earlier, NVIDIA, S3 and XGI don't sell cards themselves, choosing instead to focus their attention exclusively on the design and production of their graphics processors. While ATI sells cards, their scope of operation is limited to Canada and the USA ("Built by ATI"). ATI-based cards produced by other companies usually say "Powered by ATI".
Performance differences between cards using the same chip are the exception, rather than the norm. Cardmakers usually adhere quite strictly to the clock speed specifications suggested by NVIDIA, with a couple of exceptions. First, a few companies offer special "OC" versions in the enthusiast segment which run at higher clock speeds, and even most "normal" cards can be set to operate at higher clock speeds manually. The difference is that in the first case, the manufacturer guarantees that the card will work at the higher speed without a problem.
Graphics cards in the lowest-price segment are the second exception. Here, the competition is so intense that every dollar counts, so manufacturers may try to cut corners. Often enough, the result is either low 3D performance or bad 2D quality, or even both. Frequently, the memory bus is reduced in size, for example from 128 bits to 64 bits (see above). We can only warn you to stay away from such products, since the 3D performance suffers enormously when memory bandwidth is halved. If detailed information is conspicuously absent from the box or the salesperson can't or won't give you any technical data for the card, the best course of action is to keep looking, no matter how tempting the offer may be.
Another variation on the game of "sales poker" is the use of lures that sound good but may not necessarily be of great value. For example, while 256 MB of video memory obviously sounds better than 128 MB, the extra memory will only pay off in modern games with large textures, played at high resolutions and with FSAA and AF enabled. To be able to handle the amount of data produced in such a scenario, both the graphics processor and the memory bus need to be sufficiently fast. In other words, 256 MB simply doesn't make any sense outside of the enthusiast segment!
Image quality is a factor that is very hard to judge before a purchase. To prevent nasty surprises, you should always ask the staff about the store's return policy before you buy the card. Then test it to see if it meets your needs, and return it if necessary.
