Kriptonac,
The first and most obvious question to ask is, what is your ambient temperature?
Ambient affects all computer temperatures. Here's the temperature conversions and a short scale:
Cx9/5+32=F ... or ... F-32/9x5=C ... or a change of 1C = a change of 1.8F
30.0C = 86.0F
Hot
29.0C = 84.2F
28.0C = 82.4F
27.0C = 80.6F
26.0C = 78.8F
Warm
25.0C = 77.0F
24.0C = 75.2F
23.0C = 73.4F
22.0C = 71.6F
Norm ... or ... 22.2C = 72.0F
21.0C = 69.8F
20.0C = 68.0F
19.0C = 66.2F
18.0C = 64.4F
Cool
Ambient temperature is a huge variable. We see Threads posted here from people all over the world living in very different climatic regions, where their computers may not be in a thermally controlled environment, so ambient temperature can range anywhere from 15 to 35C.
If your ambient temperature is up around 30c, then that might explain your Core temperatures, but if your ambient temperature is somewhere near normal, then something is definitely not right for an i5 6600K at stock settings with a CM Hyper 212 EVO.
Here's the recommended operating range for Core temperature:
80C
Hot (100% Load)
75C
Warm
70C
Warm (Heavy Load)
60C
Norm
50C
Norm (Medium Load)
40C
Norm
30C
Cool (Idle)
25C
Cool
Core temperatures in the mid 70's are safe, so you don't really want to exceed 80.
Since you're already reaching 80 during gaming, which is typically not a very CPU intensive workload, then you need to find out what the Core temperatures are when running a proper
thermal test.
Click on the link above that
manddy123 provided and give it a read. Pay close attention to Sections 11, 12 and 13, which will walk you through performing a
thermal test so you can find out what your baseline Core temperatures are during a steady 100% workload. Once we know that, then we can much more effectively troubleshoot the problem.
CT