Windows BSOD 0x000000FB — RECURSIVE_MACHINE_CHECK Fix

What Does This Error Mean?

Blue screen 0x000000FB (RECURSIVE_MACHINE_CHECK) means the CPU encountered a hardware error (called a Machine Check Exception) while it was already in the process of handling a previous hardware error. This recursive failure — an error inside an error handler — is a serious sign of hardware instability. Overheating CPU, failing RAM, a corrupted BIOS, or a hardware defect are the most common causes. This BSOD always warrants a careful hardware inspection.

Affected Models

Windows 10
Windows 11
Windows Server 2019
Windows Server 2022

Common Causes

CPU is overheating due to a faulty cooler, dried thermal paste, or blocked ventilation
Faulty or unstable RAM sticks causing machine check exceptions under load
Corrupted or buggy BIOS/UEFI firmware that fails during hardware error handling
Unstable CPU overclock causing the processor to produce uncorrectable errors under load
A physical hardware defect in the CPU, motherboard, or memory controller

How to Fix It

Check CPU temperature immediately. Download HWMonitor (free from cpuid.com) and monitor CPU temperature at idle and under load. Idle temperature should be below 50°C and load temperature should not exceed 90°C for most modern CPUs.

If temperatures are high, clean the CPU heatsink and fans with compressed air. If thermal paste is old (more than 5 years), replace it. This can drop temperatures by 20°C or more.
Reset any CPU overclocking. Enter your BIOS during startup (usually by pressing Del or F2) and look for any overclocking or performance settings. Select Load Optimized Defaults or similar to restore factory settings.

Even a modest CPU overclock can cause machine check exceptions when the CPU encounters a thermal or voltage spike it cannot handle at the higher frequency.
Run MemTest86 overnight. Download from memtest86.com, create a bootable USB, and boot from it. Let it run for at least 4-8 hours or two full passes. Any errors confirm bad RAM.

RAM errors can trigger machine check exceptions in the CPU's memory controller, causing this recursive error. Bad RAM is one of the more common causes.
Update your BIOS firmware. Visit your motherboard or PC manufacturer's website and download the latest BIOS version. Follow the update instructions carefully — this is a critical operation.

BIOS updates sometimes include fixes for specific CPU and memory error handling bugs that cause this type of BSOD.
If you have multiple RAM sticks, try removing all but one and testing each stick alone. If the crashes stop with a specific stick removed, that stick is the likely cause and should be replaced.

Test each RAM slot too — a faulty memory slot on the motherboard can cause the same symptoms as a bad RAM stick.

When to Call a Professional

0x000000FB is a hardware-level error and is more serious than most BSODs. If cooling, RAM, and BIOS are checked and the crashes continue, the CPU or motherboard may be physically failing. A technician can run hardware diagnostic tools and test components individually. This error on a relatively new PC may indicate a manufacturing defect covered under warranty.

Frequently Asked Questions

What is a Machine Check Exception?

A Machine Check Exception (MCE) is an error signal generated by the CPU itself when it detects an unrecoverable hardware error. The CPU has built-in sensors that monitor for problems like memory errors, bus errors, overheating, and voltage instability. When the CPU detects such a problem, it raises an MCE signal. Windows then reads the CPU's error registers to find out what went wrong and decides whether to crash. A recursive MCE means the error happened again while reading those registers — which almost always points to severe hardware instability.

Does this BSOD mean my CPU is dying?

Not necessarily. Overheating and RAM errors are more common causes than a physically dying CPU. A CPU that is simply too hot or is running at an unstable overclock will produce MCEs without being defective. Only if temperatures are normal, RAM is confirmed good, BIOS is updated, and crashes persist should you suspect the CPU or motherboard itself.

Can I see the hardware error log from the CPU?

Yes — Windows logs Machine Check Exceptions in the Windows Event Log. Open Event Viewer, go to Windows Logs > System, and filter for events from source 'WHEA-Logger'. These entries contain technical details about what the CPU reported, including which component triggered the error. This information helps narrow down whether the fault is in the memory controller, cache, bus, or another CPU subsystem.