Efficiency
Even though the efficiency of 83.6% is about in the middle of our test group, it is still a very good value. If you look at the graph above, you can see that all PSUs are very close to each other, you will usually not see any measurable effect of one or two percents in efficiency difference.
Fan Noise
Cooler Master did a good job with the fan noise of the Real Power M850. The fan is sufficiently quiet to not be heard over any other fans in your case.