ALL chips are different and behave differently. I was luck enough to get one of the very first Q6600 chips when they first came out and have had that baby at 3.9Ghz on air. However, the later ones came with a higher Vref meaning that you can't over-juice them - the heat is simply unbearable. Tried it on a later chip and couldn't squeeze it to 3.4Ghz stable, regardless of voltage.

The kernel has different voltage configurations dependant on the frequency that the chip is running at - and dependant on the profile you are running. For example, I can't stream flv's on starving profile and it has caused random reboots. Solution? Up the vCore (load lv profile) and stability returns.

I could bang on about overclocking theory, heat generation, vdroop and waveforms but feel that somehow it would be lost....