PS-ON Signal is a pin on a 20-pin or 24-pin ATX-specified power connector used to turn a personal computer power supply unit on/off. The PS_ON pin is normally pulled high in an open-circuit, but will turn on the power supply when it is pulled low, by shorting it to the common signal (COM). Conversely the power supply is turned off when the PS-ON is in open-circuit.
The PS_ON pin can be jumpered to manually turn a PSU on.
References
"SG6516 PC Power Supply Supervisors" (PDF). Fairchild Semiconductor. Archived from the original (PDF) on 2018-08-21. Retrieved August 21, 2018. https://web.archive.org/web/20180821093928/https://www.fairchildsemi.com/datasheets/SG/SG6516.pdf ↩
"Desktop Platform Form Factors Power Supply Design Guide" (PDF). Intel Corporation. Retrieved August 21, 2018. https://www.intel.co.jp/content/dam/www/public/us/en/documents/design-guides/resellers-power-supply-design-guide-changes.pdf ↩
"How to Jump a PSU | bit-tech.net". bit-tech.net. Retrieved 2023-12-11. https://bit-tech.net/guides/modding/how-to-jump-a-psu/1/ ↩