They're up for discussion, but personally I'd consider -

vCore - 1.425v under load
PLL - 1.6v
FSB - 1.425v
NB - Doesn't really matter tbh. Might get too warm at high voltage tho.

You also have to remember that the board probably overvolts, so what you set in BIOS is probably actually more in Windows (apart from vCore ofcourse).