Well I have a friend that is wondering, he has a single fan XFX 6950 (not reference version) That he bought this summer, and now he wants to Crossfire, and the only thing he can get a hold of is the dual fan XFX 6950 version, and my question is, is there a difference between the two, or will they work fine in CF?
More about :single fan 6950 crossfired dual fan 6950
It will work fine. If one is a 2gb and the other is a 1gb then the drivers will assume the highest common RAM and treat both cards as though they have 1GB. Get a card that matches the RAM amount of the current one and that won't happen.