for 24/7 at Thuban CPU I cant recommend more than about 1.325V for 24/7. It is the point of possible degradation chip. Of course, for some benchmars play you can go higher (1.4-1.45V at air/liquid) and easily broke 30000 MHz. But for 24/7 will be limit with lower voltage about 2800-3100 MHz. Depends at chip quality.
PS:my teacher at the beginning was overclocker Chew*, I have experience with many Phenoms II chip with air or LN2....
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