Topic is pretty simple, and I don't want to incite rage or anything, but this is a simple truth I have always experienced.
I used to have a 5870 1gb. It could run BF3 on Ultra no problems...the framerates were not very high, but they went from 24-45 fps.
Enter my new cards: I managed to pick up a 6870x2 and another 6870 on the cheap (only reason I got them). They CANNOT run the game at the same settings as my 5870 could, despite having the same vram limit. In fact, it appears as if the hard drive is constantly being accessed and the frames WILL drop to 1-2 and stay there when any bullets are fired.
This goes for pretty much every driver between 11.12 and 12.3 and every combination of cap I have used. I now have to play the game on lowered detail. And yet they have the same vram. 11.11 seems better, but it now makes my screen pixelated and black and then I cannot do anything.
So is there a phyiscal explanation or what? Or are the drivers just garbage? Because I feel like an idiot now for not holding out for the gtx 670.
your x2 - IS crossfire. running the third card is tri crossfire. completely different ballgame. try going to guru3d and see if they have drivers to help somewhere in the downloads section. otherwise remove the single card and try running the x2 alone.