My three-year-old Windows 11 PC suddenly reboots without showing a blue screen when I open Wallpaper Engine and switch wallpapers. It also crashes intermittently while gaming. Event Viewer reports a fatal hardware error from the processor core: Machine Check Exception, specifically a Cache Hierarchy Error. The processor APIC ID changes between crashes.
The system uses a Gigabyte B550 Aorus Elite AX V2 motherboard, Ryzen 5 5600, Radeon RX 6650 XT, 16 GB of RAM, and an 850W power supply. Everything is running at BIOS defaults.
I have already tested the memory with MemTest86, updated and reset the BIOS, disabled PBO, tried Eco mode, repasted the CPU, replaced a 650W PSU with a new 850W Gold unit, reseated the cables, reinstalled and downgraded GPU drivers, repaired and completely reinstalled Windows, wiped the SSD, and updated all drivers. Temperatures have also become noticeably worse during gaming, sometimes reaching the limit and forcing a crash. I am trying a new CPU cooler next, but I am wondering whether the processor or another component is failing and how I can identify it.
1 Answer
A Cache Hierarchy Error is usually a processor-related machine-check failure, although unstable power delivery, overheating, or a motherboard problem can also trigger it. Since you have already reinstalled Windows, changed the power supply, reset BIOS settings, and tested the RAM, the most useful next step is testing with a known-good compatible AM4 CPU. If the crashes stop, the Ryzen 5 5600 is the likely culprit; if they continue, investigate the motherboard and cooling more closely. A three-year-old CPU may still be covered by its manufacturer warranty, so check the purchase date and warranty terms rather than assuming it cannot be replaced.
How would I handle an RMA for a CPU that is already three years old? I also do not have another AM4 processor available to test with.