Just a suggestion, I did read OP, I formerly ran CF 6970's and my first driver install was corrupted, and i cleaned it out with driver sweeper and re installed and they ran fine.
Wrong, I have seen it many many times online, usually has to do with user error when installing or driver issues. First thing you try is uninstall,driver sweeper in safe mode, then re install latest drivers.
Only cure is an air conditioner, getting better coolers for your 580's is going to add even more heat to your room, the better your pc's coolers are, the hotter your room gets.
8 is more then enough, I run 12GB, and have never seen it over 6GB usage once ever. As for BF3 load times, SSD makes the difference, has nothing to do with RAM amounts/speeds.