Holy crap, that's a lot. I heard the i7s ran a lot hotter when overclocked but that's a pretty substantial jump. Mine went from 26 to 31C and the cores went from about 30 to 40C. That's at my stock speed of 4.0GHz But then I have all the speed step stuff disabled so if I was jumping from 3.0 to 4.0 it probably would show a higher range of temp differences.