In my BIOS...which is Pheonix BIOS. You can change it in Integrated Peripherals. If not their look in the same section where you can change your processor FSB.
If American Megatrends made your BIOS, don't even both with trying to adjust anything, AM suxors. If you want to change anything in Award Bios, just play around with it. That's what i did!
BTW: Congrads to me, I got my AMD Athlon XP 3000+