Overclock until your core temperature reaches 65-70 at the max, but IME, the q6600 runs a bit hot, and I don't mind taking it up to 65-70. Some will say to stay below 55, but that would mean you probably wouldn't want to bump your vcore up much, if at all. You'd hit 3.0ghz easy, just raise your FSB from 266 to 333, and ta-dah!