Comments on: What type of power switch does a desktop computer have?

By: Oron

Oron — Fri, 13 Jul 2012 19:20:47 +0000

On ATX systems (introduced 1995) it’s a momentary connection. On earlier systems it was constant, but I doubt you are using such an ancient system…

By: Alan Wade

Alan Wade — Tue, 10 Jul 2012 13:54:29 +0000

Your PSU outputs +5 on a specific pin (+5VSB) when ever it’s plugged in and turned on.
This voltage is used to power your motherboards power control circuitry so that i can turn on when the BIOS tells it to, or when you press the button.
The power button is nothing more then a momentary SPST push button switch.
When you press it, your motherboard’s power control circuitry connects the PS_ON lead to ground, then the PSU turns on fully up and provides power to all pins. Then it sends a Ready signal to the motherboard once it is fully powered up, so that the system only starts after the PSU is ready

By: Ryan Dube

Ryan Dube — Tue, 10 Jul 2012 04:22:14 +0000

It’s a momentary pushbutton switch – in most modern systems the handling of the momentary pushbutton contact and all of the timing is handled by the PSU/motherboard.