"The BIOS allows you to adjust fsb from 100 ~ 250 Mhz in 1 Mhz increment provides extensive options for overclocking. The Vcore is adjustable from 1.1 ~ 1.85 in 0.005v increments. The manual we got here stated adustable VIO and it is infact incorrect. There is NO VIO tweak available on P4S and this has been confirm by Iwill. They will revise
their user's manual to avoid confusion. The lack of VIO tweak will be a disappointment for hardcore overclockers. However, you can easily pump the speed of P4 up 250 Mhz without increase the core voltage and it is still a significant increase in Mhz."
FULL STORY @ OVERCLOCKERS (http://www.overclockers.co.nz/ocnz/mobo/p4s/f1.shtml)