Nvidia's GeForce 7800 GT card continues the trend started with its 6800 GT predecessor: scale back the power of the top-of-the-line 3D card and offer it at a less stratospheric price. At $449, the GeForce 7800 GT certainly isn't what we'd call cheap, but it's a bit less of a sting to the wallet than the top-of-the-line $599 GeForce 7800 GTX. And for that money, you get a high percentage of the raw speed of the more expensive card, as well as full support of all the new rendering techniques that enhance both visuals and the gameplay experience.
The GeForce 7800 GT takes up a single PCI Express slot. The card uses a thinner heat sink than the GTX, which, although it's a single-slot card, has a heat sink large enough to sometimes interfere with the adjoining slot. As you can with most recent GeForce models, you can further boost the 7800 GT's already impressive performance by pairing it with a second, identical card if you're using an SLI-capable motherboard. The card has a pair of DVI ports, so you can output to two LCD monitors, as well as an S-Video port.
The card includes 256MB of 500MHz DDR3 SDRAM. The core clock on the GeForce 7800 GT that Nvidia supplied us with ran at 400MHz, but many manufacturers are overclocking their cards, with some running at core clock speeds of up to 450MHz. Of course, you can overclock the card yourself using the Nvidia CoolBits overclocking application, which is accessible via a registry tweak. These speeds compare favorably with those of the GeForce 7800 GTX, which uses 600MHz memory and runs at a core clock speed of 430MHz.
Unlike the old GeForce 6800 series, however, where the only performance difference between the GT and Ultra cards was clock speed, some minor differences exist under the hood between the 7800 GT and GTX cards. Specifically, the GeForce 7800 GT has 20 pixel pipelines and 7 vertex units, compared to 24 pixel pipelines and 8 vertex units on the 7800 GTX.
How do these differences affect performance? On CNET Labs' Half-Life 2 benchmark, the GeForce 7800 GT posted a score of 71.5 frames per second (fps) at the highest resolution (1,600x1,200), compared to 93.9fps for the 7800 GTX. While that's about 24 percent slower than the 7800 GTX, it's still more than fast enough for smooth gameplay. And it's also faster than ATI's current top-of-the-line Radeon X850 XT Platinum Edition, which managed just 60.1fps. Results were much closer in our Doom 3 tests, where the GeForce 7800 GT managed 44.7fps, compared to 50.6fps for the 7800 GTX and a mere 35.4fps for the Radeon X850 XT Platinum Edition.
Despite these scores, the Nvidia cards aren't the clear winners. Far Cry still gives them trouble. The GeForce 7800 GT managed 54.7fps in our highest-resolution Far Cry testing, respectably close to the 61.8fps achieved by the 7800 GTX. But both cards were trumped by the Radeon X850 XT Platinum Edition, which brought in 64.5fps in the test. In fact, even the ATI Radeon X800 XL, a card that's $150 less expensive than the GeForce 7800 GT, managed a very playable 50.9fps, only a few frames per second slower than the 7800 GT. The results were much closer at a lower 1,024x768 resolution, where the 7800 GT's 99.3fps results were very close to the 7800 GTX's 101.6fps and the X850's 104.5fps. Again, the less expensive Radeon X800 XL managed a respectable 2.3fps here. We saw similar results in the 7800 GTX review and conjectured that it might be due to early drivers. But it's been two months since we first tested a 7800-series card, which in our minds is enough time to work out a software kink if there was one. Whatever the case, ATI retains the Far Cry speed title, a testimony to how well ATI's cards handle Direct 3D-based games.
It's not all about pure, raw speed, though. Along with support for the Pixel Shader 3.0 special effects (introduced with the GeForce 6800 series), the 7800 series adds support for High Dynamic Range (HDR) lighting, a new feature that makes lighting effects look much more realistic; both very bright and very darkly shadowed objects look significantly better, with much better texture quality on extremely lit or dim subjects. At the moment, however, HDR lighting is showcased in only a few games: Far Cry, Painkiller: Battle Out of Hell, and Splinter Cell: Chaos Theory. Another addition is Transparency Adaptive Anti-Aliasing, which helps smooth out jagged edges in objects such as fences.