The SIO sends a 3.3V signal to the PCH indicating that the standby voltages are stable. 2. Power Button Trigger
| Stage | Time (ms) | Description | | --- | --- | --- | | Power Button Press | 0 | User presses power button | | Power-On Signal | 1-10 | Power button sends signal to motherboard | | PSU Enable | 10-50 | PSU enables output, providing power to motherboard | | Motherboard Power-Up | 50-100 | Motherboard powers up components | | CPU Reset | 100-200 | CPU resets and initializes registers | | Chipset Initialization | 200-500 | Chipset initializes and configures components | | Memory Initialization | 500-1000 | Memory initializes and configures | | Boot Process | 1000-5000 | System boots, and BIOS/UEFI takes control | desktop motherboard power sequence pdf exclusive
Finally, the CPU receives its specific reset signal and begins reading the BIOS/UEFI firmware to start the Power-On Self-Test (POST). The SIO sends a 3
The South Bridge releases the reset signal to the entire board. The South Bridge releases the reset signal to
The PSON# signal connects to the ATX PSU Green Wire. When this wire is grounded (Low), the PSU wakes up.