i have a amd a6 6400k dual core apu. with an asus a88x pro mobo. the stock clock speeds are 3.9ghz with 4.0ghz boost. i know how to change the multiplier part. i want to OC to 4.2ghz but i dont know whats a safe voltage to start off with. i installed prime 95 too. i got a basic knowledge of OC but what i dont understand is what voltage to start off at