Call of Duty 4: Modern Warfare
We tested Call of Duty 4 by recording a custom demo of a multiplayer gaming session and playing it back using the game's timedemo capability. Since this is a high-end graphics card we're testing, we enabled 4X antialiasing and 16X anisotropic filtering and turned up the game's texture and image quality settings to their limits.

Thanks to a recent change to Nvidia's drivers, we were (finally!) able to test at 1680x1050, even though that's not our display's native resolution. Consequently, we've chosen to test at 1680x1050, 1920x1200, and 2560x1600—resolutions of roughly two, three, and four megapixels—to see how performance scales.

The X2 handily outperforms the GeForce 8800 Ultra at 1680x1050 and 1920x1200, but the contest tightens up at 2560x1600, where the multi-GPU configs seem to run into a wall—probably with available memory, since multi-GPU operation does bring some overhead. The GeForce 8800 GT in SLI trounces the X2 at the two lower resolutions, but stumbles badly at four megapixels.