Something about CPU voltages

So I've overclocked my i3 540 at 3.6 ghz, but I never touched the voltages because I was scared it could do something bad. I want to know what would happen if I increased those voltages? Will my CPU temperatures lower down or will my PSU just explode?
I have a 550 watt with a 9800 GT graphics card
 


This may sound funny but I was just thinking of pushing it further xD
So CPU voltage doesn't help with temperatures?