Whether the frequency/speed will matter or not really depends on what you do with your system, if nothing more than email, light typing, surfing, etc then 1333/1600 will be fine, gaming would suggest 1600/1866 and if you multi-task, use video, image, CAD, VMs, apps or anything with large data sets then 1866 and up......big thing is to make sure of what DRAM freqs your CPU can handle - many people here seem to think if a mobo says it supports up to say 2800 DRAM, then they can just pop in 2800 and all should be good - which is just wrong - the CPU has to be able to carry the sticks and amount of DRAM at the freq