Recently I found the need to run an old computer PSU as a bench power supply, with no connection to a motherboard. Normally this is not possible, as there is protection within the PSU to ensure that it cannot fire up unless the motherboard connection is present. Luckily, this is very easy to bypass…
Simply connect the green wire to any black wire. You can use a paper clip, a piece of solder (as I did), or any other conducting wire. There ought to be one green, but multiple black wires. Just join green to any black, as per the image below.
Shorting a PSU to work without motherboard connection (green to black)
Then just get some insulating tape and tape up the paper clip, solder or whatever you used and power up the PSU. You should now have a working bench power supply!
Of course, it this blows up and destroys your house and all of your possessions, or any such scenario ensues, I am not liable for any damages incurred. It shouldn’t though, don’t worry!
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