CPU and fans at 100%, and the CPU temperature at 70-90˚c

[Jesper Heidenberg Hansen]

About 1/20 times i turn on my PC, the fans goes wild, and my cpu temperature goes to 70-90˚c. The cpu usage at 100%. It doesn`t stop until I turn the PC on and off. I have tried resetting Factory settings in Windows, but that didn’t fix it. Windows is always up to data. The problem was worse a few months ago, when it happend about 1/5 times.

My specs:
CM Storm Stryker Gaming Big Tower
Intel Core i7-6700K Skylake Prosessor
Samsung 850 EVO 500GB 2.5" SSD
EVGA SuperNOVA 850 G2, 850W PSU
Gainward GeForce GTX 1080 Phoenix GLH
Cooler Master Nepton 240M CPU Kjøler
HyperX Fury DDR4 2400MHz 16GB
ASUS ROG MAXIMUS VIII HERO, Socket-1151

 

[RememberThe5th]

How old is your water pump? It might be failing to start or the tubes are clogged up if you didn't clean AIO, usually AIO pump dies faster than custom watercooling. (thanks to @USAFRet)
Well if you have stock cooler you can try stock cooler and try to induce same problem, if it doesn't then it means that pump might died.