Nvidia or ATI

Nvidia vs. ATI video card hardware

Currently, ATI lags well behind Nvidia in the fastest-GPU race. A GPU is a graphics processor unit. It is the video-card equivalent of a CPU (central processing unit). A GPU makes all the rapid calculations necessary to display moving 2D and 3D images. Current clock speeds range from 240 MHz to 675 MHz. Faster video cards keep up with the speed in action games and smoothly display any moving images on your computer.

A video card's dedicated memory (RAM) ranges from 128 MB to 1 GB. Video cards have many other specifications discussed in sometimes excruciating detail in reviews, but you do not need to understand all of them to choose the best video card for your system and your needs. We'll talk about the important ones as we go along, but if you want to learn more, see the Best Research section below or read the buying guides on websites listed in the All Reviews section.

All current video cards are compatible with Microsoft DirectX 9. Many cards are not compatible with DirectX 10, which is part of Windows Vista, and a free download for licensed XP owners. Microsoft describes DirectX as "the core Windows technology that drives high-speed multimedia and games on the PC." Reviewers say that DirectX 10 games are trickling to market. So, if you expect to buy a new video card every year or two, DirectX 10 compatibility doesn't matter much. If you want a card that will be able to run all the new games you buy during the life of your computer, it is an essential buying consideration. Jason Cross of ExtremeTech.com observes, "No matter how fast the card you buy today is, at some point down the line, it's not going to be fast enough, or have all the new whiz-bang features you want. The real question then is: How much disposable income do you have, and what are your needs?"

Nvidia graphics cards dominate in reviews, particularly among the most cutting edge video cards. ATI cards can be competitive in the mid and lower price ranges. Reviewers often find that they are better for playing one or two games, but comparably priced Nvidia cards are better for all other games. Where ATI may have a market niche is in cards oriented to video -- displaying movies and DVDs -- rather than in gaming. ATI has long been known for cards with specialty features, such as an integrated television tuner or video capture. However, we didn't find many reviews of video cards for those types of purposes -- even in home theater or video enthusiast publications or websites.

While all video cards have a speed rating, video cards can also be overclocked. That means running a GPU at a higher speed than rated safe by Nvidia or ATI. Overclocking generates extra heat, which shortens the life of hardware and may cause system instability, failure of other components and burnout of overclocked components.

Despite that, overclocking is popular with gamers because it results in more speed at no additional expense. If you're interested in overclocking, you have two choices. You can buy a factory-overclocked card, or you can do it yourself. Reviewers cite advantages to each. Since doing your own overclocking often voids your warranty, factory overclocking protects your investment. On the other hand, you pay a little more for a factory-overclocked card, and reviewers sometimes say that a stock card can be overclocked to a higher speed than a factory overclocked card. Reviewers generally test video cards at stock and overclocked speeds.