Help with oc'ing(does anyone know how to change the voltage with Gigabyte BX2000???

[CoolCompNerd]

I can't change them so I can't oc more than 75 MHz fsb with cel466=525MHz
So Please help me; I did oc it with the dipswitches onboard my mobo but it won't go any higher than this and no I didn't use a peltier or something like that.