I am picking RAM currently and i am noticing an increase in CAS latency as you go higher in the MHZ department but does it really matter ? 1600 mhz at 7 latency or 2133 at 9 latency ?
The 2133 is better for sure, however its not worth spending much more money on it, unless you use an APU in which case the faster RAM is better for iGPU performance.