I/O voltage??

I currently own an Abit KT7A v1.3. I was going through the BIOS the other day and I noticed the I/O Voltage setting (I had never really noticed it before). I looked though the manual but it doesnt describe it in any way. What does it increase the voltage of? Will it affect my overclock in any way?

Your CPU has a Vcore voltage and a VIO voltage, the VIO stands for Volts in/out as far as I know. I have never heard of changing this for OC'ing purposes, hope that answers your question.