Voltages like 1.05V (VCCIO/VCCSA) power the motherboard's communication hubs. Stage 4: CPU Initialization (VCore) The most power-hungry part of the sequence occurs here. VRM Enable:
The Super I/O interprets these high SLP signals as the green light to activate the power supply. It pulls the PS_ON# wire (the green wire on the 24-pin ATX connector) to ground (0V).
The SIO (Super I/O) and PCH receive standby power to monitor the power button. SIO → PCH desktop motherboard power sequence pdf exclusive
Desktop motherboard power sequencing is the invisible foundation upon which every PC starts. From the moment AC power is connected to the instant the CPU fetches its first instruction, a tightly orchestrated sequence of voltages, power‑good signals, and resets must execute without error. By understanding this sequence — and having the right reference tools at hand — any technician or enthusiast can diagnose failures with precision and confidence.
For a deep dive into specific board schematics, you can find high-quality repair guides on platforms like or explore advanced board bring-up tutorials on KLS-School for a specific motherboard brand like Voltages like 1
is active-low. The SIO pulls this pin down to 0V (Ground) .
All secondary and tertiary power rails across the board are now running. The motherboard must confirm that this power is clean before turning on the processor. Power Good Handshakes It pulls the PS_ON# wire (the green wire
To provide a comprehensive understanding of the desktop motherboard power sequence, we have created an exclusive PDF resource that details the intricacies of this process. This PDF guide includes:
The PCH sends a reset signal to the entire platform (PCIe, SATA, USB, etc.).