I don't know your specs and I don't play BF3 but I did recently have an issue with my card locking up or going black and my PC restarting. I reinstalled Windows 7 64 bit and it still happened. Turned out the problem was needing a chipset driver update for the motherboard. A new video card driver and the original chipset driver from the CD had compatibility issues. Anyway, its worth a try. Best of luck to you!
Thanks I dont feel the guy I was trying to help was respectfull so dont worry about helping