I've been dealing with this for a while now. Basically, when core #3 is turned on, my computer will run for a bit, then blue screen randomly. Usually pretty quick. I have been through many reinstalls, definitely not software. Tried cleaning, re-applying thermal paste. This is a 3 year old processor, and this has been going on for about 1 1/2 years. The only fix I have is in the bios, to turn the processor off. My mobo is the Asus m4a87td-usb 3, evga gtx 570 superclocked and so on. I've also noticed, I have never been able to overclock my processor or my graphics card even little without blue screening, if that helps. Even with the auto-tune. I have a case with plenty of large fans and air flow.