Bah, HDD still corrupts with RAM running 267Mhz. Crap. Also tried to boot while DVD drive (using ATA while HDD's use SATA) but didnt matter.

Oh well, back running 251Mhz 4-4-4 timings then. Tried to enable Memory Hole but that didnt help either.

Though I dont understand why the HDD would corrupt while running high memory speed. I'd expect the PC to reboot/BSOD/hang earlier than just corrupt the HDD?