are 20 pins on a standard ATX connector. You must first locate
pin 14. This pin is very easy to spot since it's the only one
with a green wire. All you have to do to make the power supply
start is to ground this pin. All pins with black wire coming
out of them are grounds. I used a twisted paper clip to make
contact between the 2 pins (the green one and any of the black
ones). Once your pin 14 is grounded, the power supply should
turn on whenever it's switch is on. To know if it works listen
to the power supply fan, it will spin whenever the power supply
is the most basic way to use a second power supply, but it's
not very practical if you want to mount it inside your case.
You will have to stretch your harm to the back of your case
whenever you turn on your system. So the next step would be
to relocate the power supply switch to the front of the case.
For this, you will need a normal ON/OFF switch and some wires.
Simply install the switch between your pin 14 (green) and your
ground like this: