how did you overclock the cpu?
did you leave everything else on auto?
if so the motherboard automatically increased the voltages.
when you overclock you increase voltage to have better system stability meaning in my case my q6600@ 3.4ghz runs at 1.400vcore if i lower it my system will become unstable, get bsod, random crashes and yes when you increase voltage you increase the temps too so if your overclocking its recommended to have aftermarket heatsink so the excessive heat can be drawn out from your processor making its safe.
hope that helps