Change the FSB?
Ah, that's because you have a proprietary HP system board. Usually system manufacturers like Dell, HP, Gateway, etc. don't allow you to do much from your CMOS, changing the FSB/Multiplier included. You either want to buy a new system board, use a software program to overclock, or flash your BIOS from a file that is of the same exact specifications as yours, even the slightest deviation can cause you major problems.