I have i7 Kaby Lake 7700K with Asus Z170-K which I cannot make stable.
In idle mode the temperature (measured by RealTemp) hovers around 35 C, which I think is pretty normal. However, when I run stress test (with Intel Burn Test), it works OK in high load, but in "very high load" the temperature quickly goes up to 90 and eventually the system freezes. The CPU is not overclocked.
I have a decent cooler (Cooler Master Hyper 212), with thermal paste and everything. I tried multiple times to re-assemble it with different amounts of paste and different screwing techniques.
I updated the BIOS.
Still... under very high load the system freezes.