I doubt the core is good and the PSU is causing the problem. If the core is unlockable it should unlock and show, at least in BIOS, as a quad. I have an Athlon II x3 unlocked, and it shows as a phenom II x4 in BIOS. If it won't boot right and then shows as an x3 again, it means it couldn't boot with those settings and reset to the default settings- wouldn't have done that with a bad PSU I don't think. Well- let us know if it unlocks with a new PSU.