How do you get your VCore so low? I am at 1.3V for 4.5Ghz although I have left the voltage on AUTO in the bios. Are you setting it manually?
Are you making sure to set the BCLK (base clock) to 100 manually ? Also have you made sure that the memory can't run at lower volts, lowering the volts on the memory and tightening up the timings will probably give you some headroom with the Vcore.