How to short 2 pins on a computer motherboard through an arduino

I want to be able to turn on my computer wirelessly from my phone.
I have a generic Uno wifi r3 with built-in ESP8266. (Couldn’t find an original Arduino in my country)

If you don’t know, to turn on a pc (or off), you need to short two pins on the motherboard, now is there a way to do that using my Uno? and can I control it via wifi? Which pins should I use and how can I code this?

I am a complete beginner and just got my Uno yesterday.

The Uno can control a mechanical relay to connect the pins, or a solid state relay, or perhaps an optoisolator. Which to select depend on the voltage/current across the two pins.

How you command the Arduino is up to you.

I think the voltage on the PC power switch is equal to Vsb (the always-available stand-by power), so 5V.
If your arduino works with 5V logic levels, you can power it from the PC power supply (the Vsb line) and use one digital output pin connected to the unpowered pin of the power switch. Maybe add a diode just to be safe.
Make sure to not hold the pin high for long - 4 seconds normally forces a PC to turn off.

Hey, thanks for the reply.

I was just wondering, should I get a multimeter to test the voltage on the 2 pins to be safe?

if I have 2 female to male jumper cables, each one connected to each pin on my motherboard, can I code the Arduino to short 2 pins together, or do I need a relay that is controlled by the Arduino?

“should I get a multimeter to test the voltage on the 2 pins to be safe?”

That would be a good start.
There are no Arduino pins that can be programmed to be shorted together. All you could do is drive them High (nearly 5V) and Low (nearly Gnd).

If you can measure the current thru a wire when you short the pins, that will tell what kind of external hardware would be needed.

There is one and only one reason in the world why you should get a multimeter. You should get a multimeter if you haven’t got a multimeter!


Those two pins on the motherboard are a digital input and Vsb (+5V).
If your arduino shares GND with the PC, you don’t need to short these pins - just drive a short pulse to the PC digital input pin.
Imagine it is two arduino boards, one controlling the other.

If you are not sure which pin is which, upload a small sketch to show the status of two digital input pins on your arduino, then connect those pins to the ones on the PC. Whichever is high even with the PC completely off is your Vsb, the other is the input.

A multimeter is always useful, though. You should have at least one :stuck_out_tongue:

1 Like

Another option could be, and I have not tried this, an opto-isolator. This would mean no need to directly connect any wires between the Arduino and the motherboard pins. Of course, if you are powering the Arduino from the PC in some way, those wires will be connected, so the Arduino will not be truly isolated.