My PC suddenly reboots without showing a blue screen when I open Wallpaper Engine and select a different wallpaper. It also crashes during some games, although not consistently. Event Viewer reports: "A fatal hardware error has occurred," reported by the processor core, with the error source listed as Machine Check Exception and the error type as Cache Hierarchy Error. The processor APIC ID changes between crashes.
The system is about three years old and currently uses default BIOS settings:
- Windows 11
- Gigabyte B550 Aorus Elite AX V2
- Ryzen 5 5600
- Radeon RX 6650 XT
- 16 GB RAM
- 850 W power supply
I have already run MemTest86, updated and reset the BIOS, disabled PBO, tried Eco Mode, repasted the CPU, replaced a 650 W PSU with a new 850 W Gold unit, reseated all cables, reinstalled and downgraded graphics drivers, repaired and completely reinstalled Windows, updated every driver, and replaced the SSD installation. Temperatures have also become much higher during gaming, sometimes reaching the limit in games such as Helldivers 2, ARK: Survival Evolved, and Half Sword. I have ordered a new CPU cooler, but I am worried the processor or motherboard may be failing. What is the best way to identify the faulty component?
3 Answers
Also check the system’s event logs for WHEA-Logger events around each reboot and make sure automatic restart is disabled so you can tell whether Windows is hiding a stop error. The changing APIC ID does not necessarily identify the bad core; it can simply mean the processor is reporting an intermittent hardware fault. Back up important files now, because repeated hard resets can corrupt game saves and the Windows installation.
The most useful next step is to test with a known-good compatible AM4 processor, or have a repair shop test your CPU and board. If the replacement CPU works reliably, the Ryzen 5 5600 is probably defective; if the error remains, the motherboard or its power delivery becomes more likely. A three-year-old CPU can still fail, and the age alone does not rule out a warranty or manufacturer support claim.
A Cache Hierarchy Error is a hardware-level machine-check error, so another Windows reinstall or graphics-driver change is unlikely to fix it. Since the crashes happen under load and your temperatures have worsened, first verify CPU temperature with a monitoring tool and make sure the cooler is mounted correctly, the fan is running, and the CPU power connector is secure. Test with the new cooler, default BIOS settings, and no memory overclocking or PBO. If it still happens, the CPU or motherboard is the main suspect.
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