Overclocking by itself doesn't create a lot of extra idle heat. It's when you start to increase the core voltage that the idle temps will go up.

What is your room temp Chrysalis? My B2 E6400 needs an Idle correction of (++) to keep the idle temps from going below ambient when doing the low MHz / low voltage test as outlined in post#1. You should try that test and report your results. We could also use someone with an E6750 to do that test before I have to go buy one of them too.