Ok well i need some help with setting my CPU frequency etc.

I got a Asus A7V600, AMD XP 2700 and 512mb of DDR3200. It has 4 settings already in there to chose 1300mhz, 1766, 2136, 2600 or something like that, but if i chose the two faster ones my systems hangs and wont turn on.

So anyone know a site or what the settings should be