The SIO pulls the green wire on the ATX connector to ground (0V). This tells the power supply to turn on all main rails (12V, 5V, 3.3V).
In most desktop boards, the SIO will wait for 250ms after the button is released before initiating Stage 2. This prevents false triggers. desktop motherboard power sequence pdf exclusive
When an enthusiast presses the power button on their PC, the event often feels instantaneous. One moment the system is a silent collection of silicon and metal; the next, fans spin, lights flash, and the operating system loads. It feels like a simple switch. The SIO pulls the green wire on the
The guide meticulously breaks down the startup process into sequential, verifiable steps: This prevents false triggers
Typically 1.2V to 1.8V is generated first, as the CPU needs stable memory to begin execution. PCH/Chipset Rails:
The PCH or SIO enables the CPU Voltage Regulator Modules.
For more information on the desktop motherboard power sequence, please refer to the following resources: