Desktop Motherboard Power Sequence Pdf __hot__ -

The power sequence of a modern desktop motherboard (x86/Intel/AMD architecture) follows a precise chronological order to prevent hardware damage and ensure proper system initialization.

• +5VSB: present before any action (steady).
• PS_ON# asserted to main rails on: immediate on request.
• Main rails rise time: 10–50 ms (varies).
• PWR_OK asserted after rails stable: typically 100–500 ms after PS_ON# (board dependent).
• CPU reset released after clocks & PWR_OK: typical 100–500 ms after rail stabilization. (These are illustrative; consult vendor spec sheets for exact requirements.)

Introduction

• PS_ON# goes low → +12V rises after 50ms.
• PWR_OK rises 200ms after +12V stable.
• Only after PWR_OK does memory power turn on.
• VCORE begins after VCORE_EN and ramps over 5ms.
• Platform reset is the last to de-assert.

1. Executive Summary