Overclocking – Voltage

Hey,

I am currently running a C2D E6600 2.4 on an Asus P5N-e SLI, And im working on Over clocking it. I am relatively new at the whole idea. I have it clocked at 1422 FSB at 9x, 3.2ghz, and I want to push it to 3.4, but im afraid I cannot do that without Changing the voltage, but Im not sure how to go about doing that. Any Tips/Advice would be appreciated.

Thanks,
Jeff