PC Still Randomly Shuts Down During Gaming Despite Replacing Major Components

My PC continues to shut down unexpectedly during games such as Rainbow Six Siege and Fortnite. It used to happen randomly, but now it usually occurs after one or two hours of gaming. Windows has been reinstalled, BIOS and power settings changed, and I have replaced the motherboard, CPU, power supply, case fans, cooler, storage drives, and iCUE hub. I also tried plugging the system directly into the wall instead of using an extension cord. RAM tests, stress tests, graphics driver reinstalls, and command-line repairs have not found anything. The GPU and RAM are the main original components I have not replaced. Event Viewer reports Kernel-Power 41 and sometimes Kernel-Power 28. Is there anything I can try to prevent the shutdowns without immediately buying new RAM or a graphics card? The system uses a Ryzen 7 5800X, RTX 3060 12GB, 32GB of Corsair Vengeance Pro DDR4-3600, an ASUS ROG Strix B550-F Gaming WiFi II motherboard, a Corsair RM850x PSU, and a 240mm Corsair liquid cooler.