I'm overclocking my Q6600 on an G41 motherboard. The main issue I'm having regardless of voltages is if I manually increase the FSB at all the PC won't post. Default seems to be 266*9.

I tried adjusting to 280*9 but the PC wouldn't post. But I set up XMP and it defaulted to 333*7 for 1333MHz RAM speed. So I then manually set the multi back to 9 for a 3GHz CPU speed. I upped the CPU volts generously at this point to 3.625 or something from 3.250 (from what I've read this shouldn't be necessary really) and it's stable in games and runs at around 50c. I'll start bringing the voltage down if I stick with this OC.

However if I then increase the FSB to say 340 the PC won't post.

I'm using 2133MHz RAM so this should not be an issue.

The PCIE slot is locked to 100. Not sure about PCI but not using any of those slots (unless onboard audio used the PCi bus?)

I've got a EVGA 650watt PSU which should be fine.

The motherboard only has a 4pin power connector. Anandtech reckons that the socket itself delivers 47 watts so my 105Watt CPU should be sucking 58watts from the 4pin - no idea what the spec is for this power connector?

Temperatures are fine. I'm seeing 50 to 55 in Oblivion with my high voltage.