Half-Life 2: Lost Coast
This new expansion level for Half-Life 2 takes advantage of high-dynamic-range lighting, and it looks spectacular. HDR lighting requires the use of higher-color texture formats, so it really stresses a card's throughput.

The Radeon X1800 CrossFire systems manage to outdo their closest NVIDIA counterparts at low resolutions here, but things change as the resolution steps up. Nevertheless, CrossFire scales nicely from one card to two.