Motherboard power up

[Blazer78]

When the start button is pushed to activate the mobo and PSU, what component on the board actually activates it. something has to be acting like a relay or something. You push the start button shorting out the start pins and then some component latches in, starts the PSU which in turn starts the mobo, processor, bios etc. I really need to know what that component is. Thanks

 

[alexoiu]

"Normally, the PS_ON pin will be at a nominal +5V when the system is off. When you press the case switch to power on the system, the voltage at the PS_ON pin will drop to ground potential (0V), and the ATX supply will be powered on. A short time (a few hundred milliseconds) later, the power supply will send a Power OK signal to the motherboard via the POWER_OK pin (pin 8), and the system will start its boot procedure."
https://www.techrepublic.com/article/troubleshooting-pc-power-supplies/

By shorting the 2 pins on the board, you put the PS_ON pin to ground.