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0x0000009CMACHINE_CHECK_EXCEPTIONStop codeWidely reported

MACHINE_CHECK_EXCEPTION (0x9C): what it means and how to fix it

Updated Oct 21, 2026 · Checked against Microsoft documentation · How this page is made

Quick answer

Stop code 0x0000009C indicates that your computer processor detected a fatal hardware error through its machine check architecture. This crash happens before Windows hardware error reporting can start or when CPU status registers report unexpected state. Restart your computer and run the built-in blue screen troubleshooter to begin diagnosing the fault.

What it means

Windows displays stop code 0x0000009C when your processor detects an unrecoverable hardware problem through its internal error detection mechanisms. Modern microprocessors contain dedicated circuits designed to monitor execution units, internal buses, and cache memory. When a physical fault occurs that the CPU cannot resolve, it raises a Machine Check Exception (MCE).

How Windows handles machine check errors

On systems running Windows Vista and later operating systems, most processor hardware faults trigger bug check 0x124, known as WHEA_UNCORRECTABLE_ERROR. Stop code 0x9C occurs only under two specific conditions. First, it appears if the Windows Hardware Error Architecture (WHEA) subsystem is not yet fully initialized when the error happens. Second, it triggers if all processor cores rendezvous following a fault signal, but none of the cores show active error bits in their registers.

Processor architecture and error parameters

Processors report the specific nature of the failure using Model Specific Registers (MSR). For modern x64 and x86 processors supporting the Machine Check Architecture (MCA) standard—such as Intel Pentium Pro, Pentium IV, Xeon, and newer architectures—Windows lists four parameters on the crash screen:

  • Parameter 1 identifies the MCA bank number where the error occurred.
  • Parameter 2 gives the memory address of the MCA_EXCEPTION data structure.
  • Parameter 3 contains the high 32 bits of the MCi_STATUS register for the failing MCA bank.
  • Parameter 4 contains the low 32 bits of the MCi_STATUS register for that bank.

Legacy x86 processors without full MCA features, such as original Intel Pentium chips, use an older reporting format. On those legacy chips, Parameter 1 reflects the P5_MC_TYPE register, Parameter 2 provides the MCA_EXCEPTION structure address, and Parameters 3 and 4 report the P5_MC_ADDR register.

What this means for your PC

Your central processor halted execution because it detected an operational failure. Because WHEA was uninitialized or the registers cleared before Windows could catalog the event, the system stopped immediately to prevent data corruption. Resolving the crash requires examining hardware stability and referencing CPU manufacturer documentation.

Common causes

  • A fatal hardware fault detected before the Windows Hardware Error Architecture (WHEA) fully initializes.
  • Hardware exceptions recorded in processor Machine Check Architecture (MCA) status registers.
  • A processor core rendezvous where execution halts but status registers show no remaining error data.
  • Physical hardware instability on an x86 or x64 processor.

How to fix it

Safest and most likely fixes first. Readers' answers to "Did this fix it?" reorder this list over time.

  1. Run the blue screen troubleshooter

    Use this as the first diagnostic step if your computer can boot back into Windows.

    1. Open Settings from the Start menu.
    2. Navigate to the Update & Security or System section.
    3. Select Troubleshoot.
    4. Run the blue screen troubleshooter and follow the recommendations.
    Did this fix it?

  2. Decode parameters using processor documentation

    Use this step if the error recurs and you can write down the stop code parameters from the crash screen.

    1. Record the four hexadecimal parameter values displayed on the blue screen.
    2. Visit the official Intel or AMD website for your processor family.
    3. Search manufacturer documentation for Machine Check Architecture (MCA) definitions matching Parameter 1 and the MCi_STATUS register values from Parameters 3 and 4.
    Did this fix it?

  3. Restart and monitor for WHEA bug checks

    Use this to determine whether the error persists once Windows initializes its error architecture.

    1. Shut down your computer completely.
    2. Wait thirty seconds, then turn the system back on.
    3. Observe whether Windows boots successfully or produces bug check 0x124 WHEA_UNCORRECTABLE_ERROR instead.
    Did this fix it?

Is it just you?

25+ Microsoft Q&A threads discuss this. Most recent activity:

Checked Oct 21, 2026. Refreshed automatically every few days.

Sources

Frequently asked questions

Why did I get 0x9C instead of 0x124?

Windows Vista and later use bug check 0x124 WHEA_UNCORRECTABLE_ERROR for standard hardware errors. Stop check 0x9C appears only when WHEA has not finished initializing or when processor registers show no errors during a core rendezvous.

What is Machine Check Architecture?

Machine Check Architecture (MCA) is a hardware subsystem built into Intel and AMD processors that detects and reports CPU and system bus hardware errors to the operating system.

Does MACHINE_CHECK_EXCEPTION mean my CPU is broken?

It indicates a fatal hardware condition occurred, but it does not always mean permanent damage. Testing the system and checking processor register reports from Intel or AMD will help identify the failing component.

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