Do you think Vcore is all it takes to get stable?
No reason he can't get 3.8ish stable as long as temps are good.
1.65 is not crazy volts for a 65nm chip.
But yes 1.65v is a bit too high, it won't last very long at those volts.
And no of course the vcore isnt the only thing you need to get it stable, but i GUARENTEE you wont get 4ghz on that q6600. If I put 1.65v through my Q6600 I could boot at 4.2ghz