POST Code 5d - Unsupported Processor

What is POST-CODE-5D?

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.

Common 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• Outdated motherboard BIOS firmware version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

Step-by-Step Fix Guide

• 1
  Flash motherboard BIOS to latest using Flashback USB

  Most reports of POST-CODE-5D clear up after Flash motherboard BIOS using Flashback USB, so it's worth trying before anything more involved.

• 2
  Install a supported older CPU to update BIOS first

  A second occurrence often means a less common BIOS compatibility instability cause is at play, which later steps address.

• 3
  Inspect motherboard socket pins for bent contacts

  This step, "Inspect motherboard socket pins for bent contacts", specifically rules out outdated motherboard BIOS firmware version.

• 4
  Clear CMOS memory to reset CPU parameters

  "Clear CMOS memory to reset CPU parameters" targets faulty CPU memory controller channel, one of the documented causes of POST-CODE-5D.

Commands & Diagnostics

Frequently Asked Questions