What revision is your Q6600? I've had a B3 and a G0. The best I could do with the B3 was 3.2GHz. I could run 3.4GHz with the G0. That's running World Community Grid 24/7 at 100% CPU load. Both would go higher for shorter periods but not stable 24/7 at 100% load. There are guys at Xtremesystems crunching with Q6600s - 24/7 @ 100% - at 3.6GHz on air but I suspect those crunchers are a lot louder than what most of us would tolerate.
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