Hmm.....very interesting!!!
I have a 550 in another comp oc'ed at 3.7GHz via the CPU multiplier, but no unlocked cores.
My official 550 specification data sheet states the max. Vcore voltage for the 550 is 1.425v (not 1.45v).
You can probably run at 1.45v on an everday basis, but I wouldn't push it any higher.
I read somewhere that the 940 (Phenom II) can take NB voltage up to 1.50v.
But ...



