I really don't know what to say! If I had the PC in front of me I might be able to do something, but not from here. The only thing I can guess is that native power management somehow doesn't like your card.
WAIT: I JUST FORGOT SOMETHING IMPORTANT THAT I THINK I NEVER MENTIONED IN THIS THREAD (I took it for granted): have yo set DropSSDT=Yes in com.apple.boot.plist?
I don't think you should even be able to boot all cores without it, but hey, it doesn't hurt to ask.