Allow me to add my 2 cents here about RAM timings and speed:
It is going to be best to run at a 1:1 divider. If you're talking benchmarking, then you can play with it and sometimes having a higher bandwidth will make things faster. Just keep in mind that is theoretical. You are never going to see that increase really. Take a game for example, like F.E.A.R., and grab a digital stopwatch. Time a specific load time at a higher bandwidth at a ratio of like 1:2 or 2:3 etc... then time the same load time with a 1:1 ratio and tighter timings. Since this is reality you are measuring, you will see that the 1:1 ratio is performing better. Anything over 1:1 is really just a waste because your CPU can only go as fast as your FSB will let it. the RAM has no say...