the Memory Controller on your CPU is always the biggest factor to what speed you RAM will actually work at and is the Most common Problem that causes Memory to run bellow specs as it can't handle it!
usually i always get RAM thats rated 1 level higher then i plan to use it at just for stability so they run at a lower stress level EG: if i want 2100MHz i will buy 2400MHz DIMMS but your still held back by the IMC on your CPU...
