Gamespot´s Summer Video Card Roundup
In the high-end category we have to judge by two criteria: cost and performance. We have to acknowledge that some of us simply want the fastest hardware on the planet without regard to cost. For those people, the GeForce 8800 Ultra SLI provides the ultimate in performance. As expected, the GeForce 8800 GTX SLI setup comes in slightly behind the Ultras. Both the GeForce GTS 640MB SLI and 320MB SLI setups lagged significantly behind their higher-end brethren. ATI's HD 2900XT CrossFire configuration was competitive with the GTS setups but never came close to displacing the more costly Ultra and GTX SLI rigs.

If you're looking to squeeze the most frames out of your budget in the high-end category, look no further than the GeForce 8800 GTS 640MB. It sailed through our benchmarks with ease, and you can easily find overclocked variants of the card selling for marginally more than stock versions. The GeForce 8800 GTX and Ultra offer excellent performance, but the premium pricing kills the value angle. ATI's Radeon HD 2900 XT comes close to the GeForce 8800 GTS 640MB, but the GTS still maintains a slight edge in price and frame rates.
http://www.gamespot.com/features/6173135/index.html