While i was playing OWTD they were around 50-60c from what rivatuner was telling me and was running at 3700 MHz.
It's common for AMD temps to seem to bounce around especially at idle. It has to do with the algorithm used by AMD to infer core temperature from processing activity and shouldn't be cause for concern.
And one thing people always forget is that even when idle Windows isn't truly IDLE. My system has over 80 background processes running, most of them waiting for 'idle time' to do something. When one kicks off it will be a brief flurry of activity, just enough for the processor's temp sense to kick it up a notch, then idle again for a few seconds.
But that cooler definitely isn't your friend even though it looks cool...hope it complements your build's esthetics well. But if it's cooling it enough to keep it from overheating that's good enough, just be careful if you start exploring overclocking potential.