Adjusting the power supply voltage to your CPU can make all the difference between an erratically performing speed-hack and a stable screaming demon. Overclockers love to tweak every available parameter in attempts to squeeze every bit of performance out of their CPUs and system boards. Cranking up the speed is the most obvious way to get the CPU to run faster, but to get or keep it running at higher speeds you may have to jack up the CPU’s power supply voltage a notch or two. Link.
Hacking CPU Voltage to Speed Up Your PC