first off check the L1 bridges on ur chip and make sure there connected if they are great if not search the overclocking forum for one of the articles concerning connecting ur bridges via pencil or conductive pens.
once thats done just make sure that jp2 jp3 jp4 settings are right to allow manual setting of ur multiplier
then adjust ur settings in the bios until u get stable - voltage FSB and multiplier
my 800 is set at @ 1.75v with a 9.0 multiplier and FSB of @103=927mhz
ive got it higher before but since usin a stock HSF dont wanna run it too high yet.