Crossfire support?

[Kantide]

The gains from crossfire are minimal. I am running dual unlocked 6950s and get about the same performance as when windowed with one card. Radeon Pro lets you tweak the crossfire profile for a little better performance but until square or AMD get things together, you'll have to deal.

[Coldfire]

AFAIK the game does not officially support CF or SLI. But there are still ways to force it on(through the drivers or with a tool). Doing that I cannot recommend though, since it most likely will cause your game to crash at some point. Also the GPU is rarely the bottleneck for this game, so don't expect huge speedups even if you get it working.