Hardware Secrets posted an article on Voltage Configurations
>> Understanding All Voltage Configurations from the Motherboard
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