HardOCP took the BFG GeForce 8800 GTX SLI and build two systems with AMD's Athlon 64 FX-62 and Intel's Core 2 Duo X6800 processors to test their real-world gaming performance in games like WoW, NFS: Carbon, Battlefield 2142, Oblivion and a few others. They ran the games in a huge 2560 x 1600 pixels mode on their 30" Dell 3007WFP display for this test.
Here's a short snip:
We all saw tons of benchmarks last year when it came to Intel's new Core 2 Duo processors. We also saw Intel evangelize canned benchmarks that claimed up to 40% better gaming performance compared to the competition. But when HardOCP put the real world ruler to gaming between the processors, we saw little difference in the quality of experience truly supplied. What we saw was that there would be likely no way for a user to differentiate their experience between processors when playing games..
The overall conclusion is that Intel's Core 2 Duo offers a better gaming experience. HardOCP says that in some cases it became clear that AMD's FX-62 was bottlenecking the GeForce 8800 GTX SLI to varying degrees:
The Intel Core 2 Duo X6800 allowed us to obtain “free” 8X AA on the BFGTech GeForce 8800 GTX SLI in Flight Simulator X and also run at the “Medium High” scenery setting. With the AMD Athlon 64 FX-62 we had to lower the AA setting to 2X AA and reduce the scenery settings.