Hardware Secrets posted an article on Voltage Configurations

One of the oldest tricks to increase the probability of a successful overclocking is to increase the voltage from the component you want to overclock. Nowadays even basic motherboards present some voltage adjustments, with high-end models coming with a myriad of them. The problem is that even hardcore enthusiasts have a hard time understanding what each option really means. In this tutorial we will explain the exact meaning of each one of them in clear language.

Understanding All Voltage Configurations from the Motherboard