Reset the BIOS basically. That's another common reason and easy fix for a non booter - dunno why I forgot to mention it. May or may not fix your problem - if not we're into damaged hardware territory having eliminated everything else, I fear. Best consult your mobo manual. There should be a jumper probably with 'Clr CMOS' or something printed by it. It will probably be 3 pins with a jumper over two of them. You would just move the jumper over for 10 seconds then move it back. But check in the mobo manual to confirm. Removing the battery and reinserting it pretty much does the same thing. Hopefully will work - give it a go. You'll lose your overclock settings and have to redo them (or just reload them if you saved a profile).