BIOS & startup · critical

How to fixPOST-CODE-5D

POST Code 5d - Unsupported Processor

What this error means

POST Code 5d - Unsupported Processor is a critical-severity hardware BIOS/UEFI issue. Motherboard POST code 5d indicates that the installed CPU processor is either unrecognized or unsupported by the current motherboard BIOS firmware version. Commonly occurs after upgrading the CPU without updating the BIOS. It sometimes comes down to faulty CPU memory controller channel. Use the steps below to track down and fix the cause.

Before you begin

Save open work and back up important files. Note any recent driver or hardware changes. If Windows cannot start, use the startup guide first.

Work through these checks

0 of 4 complete
01Flash motherboard BIOS to latest using Flashback USB

Flash motherboard BIOS to latest using Flashback USB.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help
02Install a supported older CPU to update BIOS first

Install a supported older CPU to update BIOS first.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help
03Inspect motherboard socket pins for bent contacts

Inspect motherboard socket pins for bent contacts.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help
04Clear CMOS memory to reset CPU parameters

Clear CMOS memory to reset CPU parameters.

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help

Possible causes

  • Outdated motherboard BIOS firmware version
  • Physical mismatch in CPU socket or generation support
  • Bent contacts or socket pins in motherboard socket
  • Faulty CPU memory controller channel