I did that and do you know what happened? I'll answer you this way, I'm writing from my pc this is what happened; I changed the Control Mode from IDE to AHCI and it, magically, booted and I thought I'd never see my stuff again for I became convinced that my hard disk had ceased to be and gone to meet its maker, I believed that my hard disk had joined the choir of the invisible, but as life is full of (sometimes) good surprises you came along and did some magic (and don't argue, cause it's always magic when one knows nothing about it); I'm spechless and my fingers are tembling as I write these lines, enjoy this moment you've earned it.
What the f**k happened when I changed my BIOS?
Will it happen again?
How come (I'm really curious about this one) all the things that I did which included REPAIRING the disk didn't work? (the answer to this is, and I'm guessing, it had nothing to do with my disk but solely with the BIOS)
And the most important one: you said that I'm overclocking; how do I reset to normal values and how did that happen?! I didn't do it, did someone mess with my BIOS?! no one has access to it...
Answering your questions:
My MB is: P67A-UD3-B3 (Gigabyte)
I don't know where to look for the revison number, if it's that important pls tell me where to look for it
Windows version: 7, 64 bit, home edition.
I hope this answers your questions.