Ermm no idea what ur memory is brand or default timmings wise.
Best way is to find ur overclock ur comfy with. Then when u know the fsb ur gonna be using, drop the multi right down to 6, so cpu is'nt being heavily clocked.
And test with different timmings, being over 900mhz id probably say timings wise 5,5,5,15(18) would be best, unless u have some really high quality ram.