Tom Clancy's HAWX
Last time we tested with HAWX, we used FRAPS to record frame rates while we played the game. Doing so does work, but I had some trepidation about its repeatability, because of one thing: when you take off straight up, pointed at the sky, frame rates tend to skyrocket. The amount of time you spend nose-up in the game will affect frame rates rather profoundly. And personally, I can't play this game well without accelerating straight up from time to time. Otherwise, I run into the ground, or I just can't get targets lined up quickly.
As a result, I decided this time to use the built-in benchmark tool in HAWX, which seems to do a good job of putting a video card through its paces. We tested this game in DirectX 10 mode with all of the image quality options either turned on or set to "High", along with 4X multisampled antialiasing. Since this game supports DirectX 10.1 for enhanced performance, we enabled it on the Radeons. No current GeForce GPU supports DX10.1, though, so we couldn't use it with them.
Hmm... so the 5870 isn't much faster than the other single-GPU cards in the mix here, though it does scale nicely in CrossFire mode.
To give you some idea of the effect of DirectX 10.1 on performance here, the 5870's frame rate at 2560x1600 dropped to 52 FPS with DirectX 10, a whole four frames per second. The 4870 X2 took a bigger hit, going from 73 to 56 FPS with the change.