Thank You. FS is the only game/sim that shuts down my PC. All other game, sims and apps do not cause any problem. I find it hard to believe that the 1000w Corsair PSU, as it is new, and replaced 860w PSU that I wanted for my previous PC to sell. However, I will find some PSU testing app. Even the 860w PSU did not appear to cause any problem. As far as I know, setting the Bios to default resets the OC back to normal, or does it? Maybe someone can give me the Bios settings for the ROG Maximus XIII HERO motherboard so I can check the Intel i9-11900K cpu clock speed, and the Corsair Vengeance DDR4 3000MHz (clock speed) 2x16GB ram chips. I have already performed a hefty time consuming MEM check on the RAM, and NO problems found. Thanks for all advice and help.