If you don;t need to overclock then don't. That's where all your problems will start to arise from.
Are you happy at 400 MHz? If the answer is yes... there you have it. If your answer is no... then list down your computer parts in a new forum and ask for overclocking tips. We can't help you if we don't know exactly what's in your computer.
I hope this help?
"It is now safe to turn off your computer"
? Quantum Physics ? Light travels faster than sound. This is why some people appear bright until you hear them speak.