X.T.R.E.M.E_ICE,my E8400(VID 1.1125V)voltage set in bios
4.0GHz 1.35000v stable air
4.1GHz 1.39375v stable air
4.2GHz 1.44275v stable air
Mtex64,I have the same mobo and so far no problem at all.
So far,after 2 days of testing my conclusion is that I already rich the limit of 4.2GHz,with my memory(PC6400) and HSP(Zalman).With new memory(PC8500) and Thermalright-Ultra120Ex,can rich up to 4.5 GHz.Beyond this,only water or phase cooling can achive higher speed.
My super PI 1M is 11.266 sec with 4.2 GHz
Very good overclocking Guide for E8400 is HERE