My i5 3570k CPU used to be at 4.2GHz and now after I installed Windows 8.1 Pro, it won't let it pass 3.8GHz, oddly when I turned on my PC, it shuts off within a sec then came back on. I have ASRock Z77 Extreme4 Motherboard. What the heck happened here? I don't see any errors... I went to the BIOS, and tried to reset the settings and restarted. I went back to the BIOS and re-fix everything, I put core at 4.2GHz and pressed enter, it reverted back to 3.8GHz... I hope there's someone on here that knows what to do with this issues. Thanks in advance.