I managed to get my q6600 to 3ghz quite easily with 1.28125 vcore (in bios), 1.264 vcore with cpu-z. My Ram timings are 5-5-5-15 and my ram voltage is 1.86 (the sticks are rated to 2v max). I am running 9x333mhz and my ram @ 667mhz.
I tried out of curiosity to OC it to 3.2ghz by setting it ot 9x356, but whatever vcore I might set, it restarts before the win xp logo. Ive tried up to 1.425v and my ram up to 2v. If I set it to 8x400mhz, it restarts just after the win xp logo.
The rest of my equipment is:
crucial balistix pc2-8500
geforce 7600 gt
350w psu ONLY
Is it possible that my psu is weak and causes the restart?
A PSU wattage calculator shows that with my equipment and even with my cpu OCed to 3.2ghz with 1.32v vcore, I would need a minimum of 350w psu.
It's possible the psu isn't liking the overclock. Is pci-e locked to under 105? You can try a small bump on the northbridge and fsb termination. Set the timing on the ram to 6-6-6-18 until your happy with your overclock, then go back(once the cpu is stable) and tweak the ram.
Also keep in mind that certain mobo's don't care for certain fsb settings. For example, you might be able to boot at 357 or 358 even though it is higher than the setting that didn't work. or 355-354 and so on.