if you want the best game performance you should get ram that runs latency 2....2.5 and 3.0 is slow
it should have tight timings all together tho
my ddr400 is at 2(latency),3,3,6

you can still overclock if you want with any ram, say its timings are 2.5,3,3,7
relax those to 3.4.4.8 and you can run the ddr400 at a higher frequency