Desktop Motherboard Power Sequence Pdf Link

Pressing the power button sends a signal to the SIO, which then relays a "Power Button Out" signal to the PCH. Sleep Signals (SLP_S3/S4):

Once the board's internal voltages are stable, the Voltage Regulator Module (VRM) generates the CPU Core Voltage (VCORE) The Power Good (PG) Signal: desktop motherboard power sequence pdf