Any luck fixing this problem? I am having the same issue. I don't OC my cpu though.
My PSU is the Corsair CX750 - which is comparable to what you have. My first though was PSU problems but the recommended wattage for 7850s in crossfire is 600w. I'm fumbling in the dark with this one.
Update: I did a system restore and rolled my AMD Drivers back to 12.11. All seems well. Seems that there are a few people reporting issues with 13.1 & 13.3 beta.