I'm the last of the ati driver installed (11.6) and also installed the latest patch (patch 1.9 and dx11 ultra upgrade).

My setup is this:
I7 950 (stock)
Asus Rampage Extreme 3
6GB DDR3 RAM
ATI 5870 (Crossfire)

It turns out that this just does not work my pc the crossfire and frames, both with crossfire enabled or not, vary from 20 to 40.
How do I enable crossfire ?
Is there solution for this ?