To do it electronically, yes, you do need a pic but there's
a much simpler way to do that,as I already said. Just short
the green wire to any ground (black wires) with anything
metallic, just to check if the system boots. If that works
and you don't want your case to be open all the time,
just get a push-in/push-out switch and connect it there.
That's the "official" way of powering up an ATX PSU.
