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 these are high-end graphics configs 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.

We've chosen to test at 1680x1050, 1920x1200, and 2560x1600—resolutions of roughly two, three, and four megapixels—to see how performance scales. I've also tested at 1280x1024 with the lower-end graphics cards, since some of them struggled to deliver completely fluid rate rates at 1680x1050.

CrossFire X performance scales quite nicely to three GPUs in CoD4—almost linearly from one GPU to two to three, in fact. That's sufficient for three 3870s to outperform two GeForce 8800 GTs. With four GPUs, scaling isn't as impressive, and it's not quite enough to allow CrossFire X to overcome a pair of GeForce 8880 Ultras.