i7-8700K takes considerable cooling even at stock.
If your hyper212 is keeping you to 85c. under load you are ok.
If the temperature at idle is 10-15c. over ambient, that is ok.
The 8700K will throttle or shut down if it detects a dangerous temperature.
That is about 100c.
What is your case and fan setup?
One thing to check is that you have sufficient front air intake for the cooler to do its job.
Two 120/140mm fans should be all you need for the 8700k and a top graphics card.