Hello @angelwert84 ,
I had exactly the same problem with my 5700xt after sim update 7.
The reason was probably that the CPU was basically not utilized, meaning slow system fan speeds while the gpu was being stressed so hard, that the hot spot temperature reached 120C when entering the menu, where the PC would just immediately shutdown. 3d mark and other stress testing software did not trigger the issue. I left my default factory OC as is(didn‘t increase allowed power draw etc.) and set the minimum/maximum fps limit with the radeon chill function for MSFS for both values to 30 fps. The issue immediately stopped. The value you want to try may differ. I currently actually use a 70 fps limit, as that is more or less the barrier where the issue occurres for me with driver version 21.11.3.