Question PC randomly freezes when under load ?

Aug 27, 2021
I get random freezes of my PC when on load, happens with MSFS but also with other games.
I guess my issue isn’t related to MSFS, but maybe anyone are can help me?

Freezes are non recoverable and the PC needs to reboot every time it happens. The frequency is very random, sometimes i can play for hours, sometimes 5 minutes.
Max Temperature under full load is; CPU 64 C, GPU 76 C.

I recently upgraded my GPU from a Rog Strix RTX2070 to a Zotac RTX3080 TI Trinity & the problems started after this upgrade.
Nvidia and Zotach spec for my system says the 750W PSU should be sufficient.
I guess all my hardware works ok, since i can sometimes run for hours with no issue.

My GPU is powered with two individual cables as intended.
So i guess one of the following is the the issue, but which?
PSU quality not good enough?
PSU power cables quality not good enough (I used those supplied with PSU)
Something else?

PC spec.
CPU: i5 11600K
Cooler: 212 EVO
MB: Asus Z590 TUF plus Wifi
RAM: 4*8GB Corair vengeance 3200mhz
GPU: Zotac 3080TI trinity
PSU: Corsair RM750W (2019 model)