Hello Forum.
Very long story short my computer wwas unstable for about 1½ month after getting a new 5900x and 6900xt graphics card.. I maybe have found out why..
The new computer uses more power than the old one, so when the cpu auto boost/turbo then it can crash since it dosent get enough power.
On my motherboard i only had connected one 12volt 8 pin connector in the top corner of the motherboard, but after i also connect the 4 pin 12v1 pin power connector then my computer did no longer crash in the same game as before.
The cpu crashed the pc/games due to lack of power when it boost in some situations.
( its a bit strange they dont tell you such things in the manual of the motherboard ).
So if your pc crash try the above i hope that is a help.
Also you can try to run two seperate 8pin PCIE cables from the PSU to your GPU ( from power supply to graphics card ) instead of one cable. ( some users recommend this dont know if it matter ).
