In my BIOS, I got 10, 20, 30 % overclocking on cpu options or even increasing of fsb speed by 1mhz.. When your computer is booting, press alt+ctrl+del on bios (this usually gets you in the bios config menu).. In the CPU tab you should be able to overclock.. Howover, oc'ing a processor could cause system instability or overheating.. Your 640 Intel is pretty good, and I would leave it at that.. If you would desperately need this overclocking, try it and see if it works for you, but beware the heat factor