X64 Exception Type 0x12 Machinecheck Exception Link Page

Run for several passes to ensure the RAM-to-CPU link is stable.

Bit-flips in RAM (often detected by ECC memory but fatal on non-ECC sticks) will trigger an MCE if the CPU receives corrupted data.

The 0x12 MCE is a "Machine Check" exception (often triggered by Intel processors), indicating a hardware failure. Common causes include:

Triggered when the CPU identifies a failure it cannot correct itself, such as a parity error or a thermal trip.

ras-mc-ctl --errors

Understanding and Troubleshooting x64 Exception Type 0x12: Machine Check Exception

Problems with communication between the processor and the motherboard or uncorrectable PCI Express (PCIe) errors.

Exception type 0x12, also known as the Machine Check Exception Link, is a specific type of MCE that occurs when the processor detects an error in the link between the processor and the system bus. This error can be caused by a variety of factors, including:

# View recent machine checks mcelog --client x64 exception type 0x12 machinecheck exception link

To extract the exact MSR register data, you must load the generated memory crash dump ( .dmp file) into WinDbg (Windows Debugger) and execute the following command: !analyze -v Use code with caution.

: Link 0x2 mapped to the PCIe root port link attached to an NVMe storage array. The storage array’s PCIe link was negotiating at Gen4 speed, but the CPU only supported Gen3. The resulting CRC errors overflowed the PCIe AER log and triggered a fatal Machine Check Exception.

WHEA_UNCORRECTABLE_ERROR (124) A fatal hardware error has occurred. Parameter 1: Bank number (0x3) Parameter 2: MCi_STATUS = 0xfe000000000c0f35 Parameter 3: MCi_ADDR = 0x1a3f0000 **Link: UPI Link 1 - Poisoned packet**

Indicates if a subsequent error overrode a previous error log. Run for several passes to ensure the RAM-to-CPU

: MCEs, and by extension exception 0x12, are inherently complex due to their close relationship with hardware architecture and low-level system software.

The , often labeled as a Machine Check Exception (MCE) , is a critical hardware-level error indicating that a processor has detected an internal, uncorrectable, or catastrophic error.

Unlike a standard 0x0 (Divide by Zero) or 0xD (General Protection Fault), exception vector 0x12 does not originate from the operating system’s memory manager or scheduler. It originates from the embedded inside modern Intel and AMD x64 processors.