Yes I understand that however they overclock similarly. Disable the auto settings and features such as power saving and turbo boost. See what you volts read when on auto and then swap to manual and put in the stock volts you saw. 1.35v is a good starting point.
Try putting the clock multiplier up a bit till you get a target speed of 4.0ghz. Boot into windows and run prime 95 on small FFT for 10-15mins. If no cores fail and your temps stay under 62c you can bump up the multiplier more and retest.
By all means don't take my advice as expert since I'm a rookie overclocker but 4.2ghz was easily manageable at stock volts. I have seen similar results with people overclocking the 8320.