"Is possibile to use just the monitor w/o power the mainboard?" için yanıtI’m leaving this answer here for posterity. I have done this by removing the entire motherboard and drive assembly. you need to tap together the power on line on the power supply. These will be the brown and purple wires at the end of the atx connection. You can wire a switch to them so you can turn the monitor on and off, otherwise it will be always on if it is plugged in.