I have 2 HD 6950 2gb's in Crossfire. And Skyrim detects my hardware as a single Nvidia 8800 GS with 512mb. This causes the game to run like shite because it isnt properly utilizing my video card/cards at all. Causes the game to run unplayable.
I figured it out. It was due to a skyrim tweak i had tried to improve the poor performance on the game.
For the record, yes, Skyrim is the ONLY game that performs poorly on my system. Though I am not the only one, it has issues with crossfire systems right now. I mean i can run Battlefield 3 with everything on Ultra 2xAA, everything else on max at 4800x900 and get 50 FPS average. Which is pretty decent for that resolution.