When the power supply sees PS_ON# hit ground, it switches on its primary internal rails, flooding the motherboard with: (For CPU VRM, GPUs, and fans) +5V (For USB, drives, and logic) +3.3V (For PCIe slots and basic IC power) RAM and Chipset Voltage Rails
Understanding the desktop motherboard power sequence can help troubleshoot issues related to power supply, CPU, memory, and peripherals. Here are some troubleshooting tips:
Now that power is stable, the logic chips can begin "thinking." desktop motherboard power sequence pdf exclusive
The SIO pulls the pin (green wire on the 24-pin connector) to ground. This is the master enable for the ATX PSU.
For in-depth diagnostics, you must monitor specific signals using a multimeter or oscilloscope: : Real-time clock battery power. : Signal from SIO to PCH. When the power supply sees PS_ON# hit ground,
The power supply monitors its own internal rails. If +12V, +5V, and +3.3V are stable for a few hundred milliseconds, the PSU sends a 5V signal up the grey wire of the ATX connector called PW_OK .
: The SIO sends this 3.3V high-level signal to the PCH to notify it that standby power is stable and the system is ready to be "resumed". 2. Triggering Phase (Power Button Event) For in-depth diagnostics, you must monitor specific signals
The final "Reset" signal is released; the CPU begins fetching BIOS instructions. 🔍 Key Troubleshooting Checkpoints
This is the most common symptom and typically indicates a failure somewhere in Phase 3 or 4:
To continue expanding your technical documentation database,Intel specific startup signals , or explain how to use a effectively. Share public link