I am trying to figure out where the power switch plugs into the dell optiplex 390 motherboard, i tried plugging it in different positions but the pc keeps booting up itself without me pressing the power button.
The black + yellow are the ones that need to be shorted in order to start the system. As in the above picture, to get rid of that error message (you don't necessarily need to) yellow + red need to be shorted permanently (a piece of metal touching both... can be soldered).
Here's a thread regarding the problem with more info from Dell's forums:
The black + yellow are the ones that need to be shorted in order to start the system. As in the above picture, to get rid of that error message (you don't necessarily need to) yellow + red need to be shorted permanently (a piece of metal touching both... can be soldered).
Here's a thread regarding the problem with more info from Dell's forums: