CPU errors and instability

Processor problems show up as hardware stop codes, freezes and random restarts.

When the processor runs into trouble, Windows usually reports it as a hardware stop code such as WHEA_UNCORRECTABLE_ERROR or MACHINE_CHECK_EXCEPTION, or the PC simply freezes or restarts. The stop code tells you that the processor reported a problem, not which part caused it: overclocks, cooling, power delivery, the BIOS and memory all play a role.

That is why the guides below start with settings and firmware before suspecting a faulty processor.

Before you change anything

Write down the stop code, or read it from Event Viewer > Windows Logs > System (BugCheck event 1001) if the PC restarted too quickly.
Note whether the problem happens under load (gaming, rendering) or at idle.
Write down any overclock, undervolt or memory profile (XMP or EXPO) you use, and your BIOS version (Win + R, msinfo32).
Check the CPU temperature under load with a monitoring tool and compare it with the processor maker's limit.

Hardware errors reported by the processor

The processor or platform reported an error it could not correct, or a core stopped responding.

Processor

WHEA_UNCORRECTABLE_ERROR

Windows stopped because a piece of hardware reported an error that could not be corrected. WHEA (Windows Hardware Error Architecture) is the part of Windows that collects these reports, so the stop code says who…

critical · Open step-by-step guide Processor

MACHINE_CHECK_EXCEPTION

The processor detected a hardware error it could not correct and stopped Windows to prevent data corruption. On current Windows versions the same event usually appears as WHEA_UNCORRECTABLE_ERROR (0x124); the older…

critical · Open step-by-step guide Processor

CLOCK_WATCHDOG_TIMEOUT

Windows stopped because one of the processor's cores did not respond to a regular clock signal in time. Microsoft explains that the core is usually unresponsive or deadlocked.

critical · Open step-by-step guide Windows & BSOD

UNEXPECTED_KERNEL_MODE_TRAP

Windows stopped because the processor raised an error (a trap) inside the Windows kernel that the kernel could not handle. A common example is a double fault: an error that happens while the processor is already…

critical · Open step-by-step guide

Sudden restarts and shutdowns

If the PC turns off without a visible stop code, the restart event in Event Viewer tells you whether it was a crash or a power problem.

Windows & BSOD

EVENT-ID-41-KERNEL-POWER

Event Viewer shows a critical Kernel-Power event 41 after the PC restarted or shut off on its own. Its text is "The system has rebooted without cleanly shutting down first", and Event ID 6008 (an unexpected previous…

high · Open step-by-step guide

First steps for processor problems

These checks address the causes that appear across Microsoft's documentation for processor-related stop codes. Do them in order and test after each.

Load the default BIOS settings and turn off CPU overclocking, undervolting and automatic boost tuning.
Turn off XMP or EXPO memory profiles for testing.
Update the BIOS/UEFI from your PC or motherboard maker; updates include processor microcode.
Clean dust from the CPU cooler and fans, and check that the cooler is mounted firmly.
Install the latest chipset driver and Windows updates.
Check that the CPU power connectors are fully inserted and the power supply is sufficient.
Run Windows Memory Diagnostic (mdsched.exe), because faulty memory can produce the same stop codes.

Sources

Written and reviewed by Matyáš Rada.

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