I've tried vNB 1.25v, vFSB 1.2v and vPLL 1.5v at FSB 500 and also vNB 1.4v, vFSB 1.3 and vPLL 1.6 at the same FSB freq and everything was ok. My system booted fine.

Maybe this issue reported by BarboneNet has something to do with mobo rev.