Raise CPU voltage to 1.39/1.40v & lower HT frequency to 2000MHz; CPU-NB should be @ 2000MHz too. Your board supports AM2+/DDR2 combo, but i think you can still feed OC with as much CPU-NB frequency & CPU voltage to balance out this OC. How high can the RAM overvolt if you OC? Play with it too, as well as with RAM timings. In theory 2000MHz CPU-NB frequency should be a f***load lot of headroom to balance out 4.0GHz with the rest of the settings i gave; if not - lower it. Just my 2 cents, not that i urge you to do it - merely suggesting.