Electricity takes time to stabilize. If a chip tries to read data while a voltage rail is fluctuating, it will corrupt. The "Power Good" phase prevents this.
Buck converters on the motherboard then generate specific voltages for DDR RAM (e.g., 1.2V or 1.5V) and the PCH core . desktop motherboard power sequence pdf
| Stage | Description | Time (ms) | | --- | --- | --- | | Power-On | Power button pressed | 0 | | PSU Enable | PSU enabled, power supplied to motherboard | 10-50 | | VRM Enable | VRM enabled, CPU voltage regulated | 10-100 | | CPU Reset | CPU reset, registers initialized | 10-100 | | Chipset Initialization | Chipset initialized, components enabled | 100-500 | | Memory Initialization | RAM initialized, contents refreshed | 100-500 | | Peripheral Component Initialization | Peripheral components initialized | 500-1000 | | Boot Device Detection | Boot device detected, boot process begins | 1000-2000 | Electricity takes time to stabilize
Before the PC is turned on, the Power Supply Unit (PSU) provides a small amount of power, typically +3.3positive 3.3 Buck converters on the motherboard then generate specific