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 some of the less expensive cards, since some of them struggled to deliver completely fluid rate rates at 1680x1050.

Well, the Radeon HD 3870 1GB is slightly faster than the stock 512MB GDDR4 version, but the margin of improvement is minor. More than likely, the improvement comes from its higher GPU clocks and lower memory latencies, not the presence of additional RAM. At 2560x1600, where memory is most likely to be at a premium, the 1GB is only a smidgen quicker.

Meanwhile, the GeForce 9600 GT outperforms both of them.