Author Options:

How do I manually turn on a computer powersupply?? Answered

I want to turn my old 480 watt computer power supply into a bench power supply, but I have no idea how to turn the thing on without connecting to the computer. The power supply is a 480 watt Reactor. I heard there is a standby 5v, and will turn on full power when you give it some logic input. Please post. Thx


Computer power supplies are of the "Switching" variety. It's very important that a load be across the +5 line before turning it on. This will allow the supply to regulate all the other lines. I've always used an old hard drive to supply the load. Yes, just attaching a momentary contact switch between the green wire to ground will power it up and down. Some require holding the power button for 4 seconds to power down. Now, if it's an old Mac power supply, the green wire needs to be connected through a transistor switch to the trickle line (pink?).

i have one thats purple to black... usually the only single color


11 years ago

Some computer PSUs require a little current to get started. If it doesn't start up when you short black and green, or the fan just wiggles back and forth.. try connecting a harddrive to it and try again.

Use a paperclip to short the green wire to a black ground.