SSD problems in AHCI mode

Last week I was playing a game when suddenly I got a BSOD. I narrowed the error down to a memory problem and ran Memtest86+. I got errors (about 30 in 15 hours). The stock timings were pretty aggressive so I loosened them and it ran without problems. Then me, being the idiot I am, decided that I might try and OC the RAM since I already had memtest in the machine. Well I messed up and had to clear CMOS, restored my known good settings including the boot drive in AHCI, and tried to boot Windows and got an error along the lines of "key hardware inaccessible." When I checked the boot order, my boot drive didn't show up but it showed up in the storage drives menu, meaning that it was still recognized by the motherboard. When I switched the boot drive to IDE, Windows booted fine. I checked the registry setting that's need for AHCI called something like "msahci" and the setting was correct. Can anyone tell me what is going on or tell me how to fix it?

This is what I referred to in my original post about the "msahci" registry value. The tutorial your posted is to modify the "msahci" to the correct value, which was already done prior to the problem and hasn't changed since then. It was the first thing I checked.