Over clocking is trial and error basis. So no one can assure a number that will give you best performance. My advice will be to use different settings and see the performance and select the best that you think.
P.s To check the performance of the system you can use utilities available online.
thank you for the reply.
i have been testing now for about 6 hours and i see only marginal speed differences between the two.
the real speed differences come into play when i start goofing with timing of the ram.
even then the latency is so small i think in modern systems its best to have the higher bandwidth more than the miniscule differences in latency.