Our Summary and Conclusion
Performance Summary: The Diamond Viper HD 2900 XT 1GB performed well throughout our tests, but its higher capacity and faster frame buffer did not result in very large performance gains. Generally, the Viper HD 2900 XT 1GB was between 1% and 12% faster than a reference 512MB Radeon HD 2900 XT; some of its larger gains came at higher resolutions with games like F.E.A.R. and S.T.A.L.K.E.R. In comprison to stock and factory overclocked GeForce 8800 GTS cards, the Viper HD 2900 XT 1GB's performance falls somewhere in between the two, winning in some tests and losing in others. And overall the GeForce 8800 GTX was clearly the best performer.
The Diamond Viper HD 2900 XT 1GB is arguably the most powerful ATI GPU-based video card on the market. With it's 1GB of fast GDDR4 memory and 512-bit memory interface, this card offers an impressive 128GB/s of peak bandwidth. Unfortunately, with an R600 clocked at 742MHz, it seems the GPU just can satisy the frame buffer's hunger for data fast enough to significantly impact performance. As our overclocking tests showed, there is some serious headroom left in the GPU so better-than-stock performance is almost a given with these cards. But better than stock still puts it on about the same level as a factory overclocked, yet more affordable, GeForce 8800 GTS. In fact, at about $499 - $530, the Diamond Viper HD 2900 XT 1GB costs about as much as a GeForce 8800 GTX, which is a much higher performing card overall. We also found the GeForces to be quieter and as out testing showed in our initial launch coverage, NVIDIA's cards consume less power too. The Radeon does offer some more features and anti-aliasing modes, audio over HDMI, and a copy of Valve's Orange Box, which enhances its value proposition somewhat, but at its current price point this card is a tough sell.