Since you are a bencher, then the highest possible clocks with the lowest possible timings is your goal.
As the IMC is in the CPU chip, the hotter it gets leaves you with less headroom for CPU OC
From my own experience, 1600MHz is the sweet spotwhen it comes to RAM OC in AMD systems in terms of performance (and please do correct me people if you have seen something different)
Since you plan on benching,I suggest that you use only 2 modules of RAM for starters to see how it goes. That is to avoid the heating issues I mentioned above, and because AMD systems tend to downclock RAM to the divider previous to the actual RAM speed when 2 or more memory slots are populated,so,be prepared to apply the timings manually.
Also,raising the NB Freq helps a lot.
That for starters. I know there is more to it,and I apologise beforehand, but working shifts takes its toll on brain functionality.