Voltage running through the "On" button

[Gibraltar]

Just curious if anyone knows what voltage is sent through the Power button header to actually turn the pc on?

 

I know a power supply supplies 3.3v, 5v and 12v, but I'm curious as to which of those is actually sent through the "on" button.

 

The reason for this is I want to put in a wireless momentary relay so I can turn the PC on from across the room, I don't like leaving my PC asleep or hibernating, I like it off, but it's a pain and I'm lazy to get up and walk to turn it on.

[dcgreen2k]

It seems to use 5V, although this actually doesn't matter for your use case. All you need to do to turn the PC on/off is bridge the two power switch pins, using a relay or transistor. This is the same reason you can turn a PC on with a screwdriver if you don't have a power button hooked up.

[mariushm]

The chipset is powered with 5v stand-by from power supply, and it will "pull up" the "power on" pin to 5v  (or some voltage like 3.3v if it's produced inside the chipset).  When the button is pressed, this pin is shorted to ground and the chipset detects this drop in voltage and knows to start the motherboard, if the pw_ok (power ok) signal indicates the power supply is ready to start and provide all the voltages.