Mix-Match is a bad idea, and the memory needs 'should' be installed in pairs.
At best mixing you only get the WORST of each.
1600 9-9-9-24 @ 1.6V ; often 1600 rated also has lower CAS at lower speeds.
1333 7-7-7-25 @ 1.5V
1333 9-9-9-25 @ 1.55V ; so the s-l-o-w-e-s-t wins - IF it will work. Review your Manual 9/10 it states 'PAIRS'.
^+1 @ tecmo34