This 5V pin works as a signal to indicate when the PC is powered down.
This 5V pin works as a signal to indicate when the PC is powered down.
My server tends to stay on instead of shutting down when told to restart. At university, my mum works full time and isn’t always available to turn it on. I have a spare 5v relay and thought about connecting it to the power button circuit so it shorts the circuit when power goes out. Initially, I tried linking it to a USB cable, but those ports still receive power even when the PC is off. I need a motherboard pin to connect to the relay’s data pin—this way, when power turns off, the relay shuts down and the power pin gets shorted, allowing the PC to restart. Diagrams are attached to clarify my previous attempts and what I’m aiming for.
The simplest method to verify power is to inspect any connector other than the 24-pin one. The rest remain inactive until the PSU receives a signal to activate. Molex is likely your best choice because it’s the most straightforward to connect.
Red provides a +5v supply. The power LED connections typically range around 2v, and the limiting resistor is built into the circuit rather than attached to the LED itself.
The main issue I notice is the timing between the power outage and shorting the power switch. Some systems include a built-in delay that prevents immediate response, requiring a capacitor to maintain relay coil energy beyond that gap. You may need to adjust the setup, but it’s possible you can work with just a relay.
Power LED remains active even when the PC is powered down. It seems adding an ESP8266 might be necessary, along with better logic since the ground connection could be faulty. Including the ESP8266 would also introduce a small delay to handle potential server restrictions.