Windows 8 Boot Problems

[pwelch12]

Hello,
( Long-post sorry i am kind of desperate right now) I have received a gaming computer and got windows 8 64 bit. I installed windows 8 64 bit to my only 1tb hard drive I had (which was from my old computer) and that hard drive also had windows 7 home premium on it. Now set up was simple-ish and I got it working, choose my color scheme and I wanted to personalize my start menu and it said that I needed to activate windows in the settings went there and it said my product key was already being used on another pc. So I kind of ignored that downloaded everything I wanted updated and shutdown and then played some games.
I saw a "update and restart" option when I was shutting down and I was going to do that today got on today did that update and also turned down the overclock from 4.2 to 4.0 and just put the voltage on auto. Turn it back on and wanted to play a game and a blue screen, it said "kmode_couldn't_be_handled or something like that so I was like well I just downclocked it so why is it saying it failed?? Put it back and now more blue screens, freezing when it is just turning on and things like EFI Shell popping up then I found out that typing exit can make you go to the BIOS did that and put my boot device to my 1tb hard drive it started up got to the spinning dots and the logo and it was just finishing then quick blue screen and it reboots to do the EFI shelling thing again!!  
HELP
PC Specs:
CPU: Core i5-2500k
CPU Cooler: Cooler master Hyper T2
Motherboard: MSI Z77A-G45
GPU: GTX 670 Twin Frozr power edition
PSU: Corsair CS550
Case: Corsair 550D

 

[CoolaxGaming]

Um pretty sure windows cannot mess with BIOS and stuff

[TetraSky]

Even if you say you downclocked it... that has nothing to do with windows. And 4.0 is still an overclock...
Load default settings of the bios, stop touching it and then try to see if windows works or not.

If yes, now try to get your overclock back. If not, there's a problem with windows.

And unstable overclock can do that.

[pwelch12]

I did put it back to stock GHZ and it loaded up with the logo and it blue screened quickly and shut off then rebooted