I've been running 2 XFX 1gb radeon HD 4850's in crossfire in my system and i recently upgraded to 2 XFX 2GB radeon HD 7850's to run in crossfire. I had a clean install and have them both operating in crossfire fine, but now I'm getting constant BSOD's on battlefield 3. I've turned the fan speeeds to 100% to keep them from overheating, i'm not overclocking them. I can run the game for about 5-10 minutes before the blue screen hits me. The codes on the BSOD are:
cpu overclock problem. not to mention that cpu will bottleneck even a single 7850, and crossfire isn't worth poop by the time the frame arrives at your screen (or in some cases it doesn't). I suggest selling your cards, platform upgrade to an i5, and stick with a single card if you want to run amd cards, until they fix their crossfire issues. you will notice removing a 7850 will probably give you smoother gameplay.