I ran the Prime 95 stress test for over half an hour. Within a few minutes the CPU temp was up to 55C-56C and the mobo 32C, but they stayed there for the duration of the test. Is this good enough?
The 3 case fans are on an external controller. I found that turning them from highest to lowest during the test seemed to cause a difference of only 1C, which suggests to me that the CM Hyper 212+ is managing ok. (Although to be fair there is not that huge an rpm diff between the highest and lowest settings of the case fans).