I did extensive testing with my rams running different timings and frequencies, and basically in terms of timing settings the only ones that makes any differens are the x-x-x and if you can run them in T1 or T2, the rest is neglectable. (T1 is close to impossible with more than 1 stick per channel btw.)
Also for clarification;
Lower timings = lower response time = better performance for gaming in general (apart from loadtimes
)High frequency = more bandwidth for bigger operations.
1066mhz and 1600mhz ddr3 made close to no difference at all in a gaming environment in my amd system.
They key was to overclock the internal northbridge and push really low timings with a low frequency (though obviously not the same for intel systems.)
5-5-5-16 @ 1333 made it purr like a kitten.