With your CPU and mobo if OCing at all, then 2133 should be fine, some 3570Ks can run 2400, but 2133 is a good safe bet. Would look at Snipers or Ripjaws X in 2x4GB. 1600 is fine for gaming if doing imaging, video, etc, may want to get the extra bandwidth from 1866 or 2133 😉