The 650i chipset is NOT overclocking friendly.
As much as I hate to agree with roadrunner on this, you really need another motherboard to overclock your Q6600.
Grimmy tried getting a moderate overclock out of his Q6600/650i combo in This Thread.
He ended up cracking the Nb after adding a bunch of extra cooling to it.
i know this is an old thread but im sure peole are still googleing about this so i have a solution. i have almost the same exact setup and i have easily gotten my q6600 to 3.2ghz with this board. all with a 1.45v, this isnt the best overclocker but 3.0 ghz seems to be the best setting since the cpu can sit with a voltage ov 1.34v and stable as can be but that could just be my cpu. the trick is to eleminate the vdrop via pencil mod. google the pencil md to eleminate and get better overclocks. hope this helps.