PHASE0_EXCEPTION (0x78)

What is 0x00000078?

0x00000078 shows up as a critical-severity Windows operating system fault. An unhandled exception occurred during the early boot phase (Phase 0 initialization). Commonly caused by unstable hardware overclocking, outdated CPU microcode, or incompatible RAM memory blocks. It sometimes comes down to CPU core voltage instability or sag. Work through the steps below in order.

Common Causes

• CPU core voltage instability or sag
• Processor microcode out of sync
• Unstable memory timing configuration (XMP)
• Outdated motherboard BIOS firmware

Step-by-Step Fix Guide

• 1
  Reset BIOS configuration to stock defaults

  The highest-success first step is Reset BIOS configuration to stock defaults, which targets the most common trigger behind 0x00000078.

• 2
  Disable XMP/EXPO memory profiles in UEFI

  Where the fault comes back, look to the later steps — they're built around uncommon boot-up instability triggers.

• 3
  Flash motherboard BIOS to the latest version

  "Flash motherboard BIOS to the latest version" is worth trying when outdated motherboard BIOS firmware turns out to be the culprit.

• 4
  Run RAM diagnostics overnight using MemTest86

  Still seeing 0x00000078 after that? "Run RAM diagnostics overnight using MemTest86" is the next thing to check.

Commands & Diagnostics

Frequently Asked Questions