Nvidia's new flagship graphics card, the GeForce 7900 GTX, offers better performance at a lower price than the 7800 GTX board it replaces. Best of all, unlike the hard-to-find 512MB 7800 GTX models, you should be able to actually purchase this card (if you have the funds); after an initial scarcity, it appears that GeForce 7900 GTX cards are now readily available from numerous retailers. ATI's new Radeon X1900 XTX card gives the GeForce 7900 GTX stiff competition for the top spot in single-card configurations, but in dual-card SLI mode, the GeForce 7900 GTX walks away with the performance crown.
Design and features
The GeForce 7900 GTX is very similar in design to its predecessor, the GeForce 7800 GTX. The primary differences? The new card is cheaper and faster. Nvidia's suggested retail price for the 7900 GTX is $500, where the GeForce 7800 GTX came in around $600. A stock GeForce 7800 GTX has a core speed of 430MHz paired with 1.2GHz memory; the new card's stock speeds are 650MHz for the GPU and 800MHz for the memory. The 7800 GTX was also available in both 256MB and (more rarely) 512MB versions, but with the 7900 GTX, you have only one choice: all of the 7900 GTX cards you'll see sold from a variety of resellers will include a full 512MB of memory.
Like most modern 3D cards, the GeForce 7900 GTX requires a direct connection to your PC's power supply. You'll need not only plenty of wattage--Nvidia recommends 350 watts for a single card and 500 watts for SLI--but also a high amperage rating on the 12V channel (22A for one card, 30A for two) that powers the graphics cards. We suggest looking up your power supply make and model on the Web and searching out its specs to be sure.
Advanced users who want to try to overclock their cards will have to edit the registry on their computers to enable Nvidia's Coolbits feature to overclock the card. If you want an overclocked card but don't want to go through the hassle, PNY, BFG, and others sell factory-overclocked versions that should grant you a few extra frames per second.
Along with standard support for antialiasing and other modern 3D graphics features, the 7900 GTX also supports transparency adaptive antialiasing, which helps smooth out jagged edges in see-through objects, such as fences. The card also supports SLI antialiasing when you use two cards in an SLI configuration; the feature sacrifices the performance boost offered by the second GPU and instead uses the second card to improve the antialiasing quality. This produces impressive results and is useful in games where you already get good performance on a single card.
Another way you can put SLI to good use is by having the second card take over certain physics calculations from the CPU, ideally resulting in more complex onscreen action. There are no games out yet that support this capability, so we can't test it; all we can do is speculate. Without going too far down an imaginary road, if the added physics effects don't truly impact the gameplay and are merely cosmetic, turning the physics on might not be worth the drop in frame rate.
The 7900 GTX supports Nvidia's full suite of PureVideo features, such as hardware-assisted decoding of MPEG-2, WMV9, and H.264 video and inverse telecine to improve the quality of DVD movies originally filmed at 24 frames per second (fps). As of this writing, however, no 7900 GTX cards have shipped that support the HDCP digital rights management technology, which will be needed to play back some HD-DVD and Blu-ray movies at full resolution. We've heard of HDCP-compliant 7600 cards, but none have been announced that use a 7900-series GPU.The GeForce 7900 GTX features a pair of DVI outputs, as well as a seven-pin connector that accommodates both an S-Video port for connecting analog televisions and an external component-output dongle for use with HDTVs. (Of course, you can use DVI to connect to many HDTVs, as well.) Both DVI connectors support dual-link DVI, allowing you to drive two large flat-panel monitors at resolutions up to 2,560x1,600.
Thanks to its increased speed and massive 512MB of memory, the GeForce 7900 GTX makes a significant performance jump over the previous-generation 7800 GTX. On F.E.A.R. (one of today's most demanding titles) at 1,600x1,200, we noted a 40 percent increase in frames per second on the 7900 GTX compared to the results from its predecessor. The 7900 GTX can't quite overtake ATI's Radeon X1900 XTX on F.E.A.R.; at every resolution the ATI card takes the lead by a few frames per second. If you look at the Half-Life 2: Lost Coast demo results, the GeForce 7900 GTX pulls ahead at higher resolutions, but with a frame rate of 63fps at even 2,048x1,536, the Radeon X1900 XTX is by no means slow. Either card will make your gaming life happier in single-card mode, but we found that when you double up, the story changes.