Maybe in some cases you want to test an old CD-Rom Drive or something else.
All that you have is a PSU from an old PC an a wire.
Here I show you how do to it.
Step 1: Search!
Follow it to the 20 or 24pin ATX plug.
The green cable is in a way the "reciever" you need to power up the PSU
Step 2: Connect!
Bend the wire and close up the little green plug from the big ATX plug to any other BLACK plug. Cause the black is the ground. To come off best you should connect the green with black besides the green.
Your PSU should power up immendiatly!
You are done!
Use a thicker cabel for this. a standart one will cause a loose connection witch
isn't good for the PSU.
When you do this make sure that you have some device(s) connected to the PSU. Otherwise your PSU tries to drive the non-existing device an will overheat.
Step 3: Extra Options
simply bend 2 wires like I do in the pictures an stick them into the black and the green port of the ATX plug and the other ends into the switch.
Ready to go!
BTW: I'm German. Maybe my English isn't so good....