Firstly, this is not recommended as a permanent feature (although I'm using it as one). It's suggested that you ensure your PSU will be under at least 10% load when you power up.
Secondly, you're dealing with live electrical supplies here, so be warned that it's possible you might kill yourself. Don't blame me if you do!
You take the advice below as-is, with no guarantees of accuracy, and you follow the instructions completely at your own risk!
OK...So you want to get your ATX Supply working without attaching it to a motherboard. Why? There's many reasons -
- You're running PC hardware but it's not actually a PC (my scenario)
- You're not sure why your computer won't start, and are looking to error-test all the components
- Insert another possible reason here
- Ensure your Power Supply is unplugged from the mains.
- Get a paper clip, ideally one that's coated (but any will do), and straighten it out.
- If you are using a coated one, strip back to bare metal about 5mm on each end.
- Insert each end into Pins 14 and 15 of your ATX powersupply connector (the one that normally connects to the motherboard). There's an image below to show you which Pins these are.
- Plug in and, if required, turn on your PSU - the normal computer power button won't work, so check if there's a flick switch on the back of the PSU.
- If your power supply is working, then it should power up - the fan should start spinning. You can now use this as a normal PSU.
Just insert one end of the paperclip into each Pin hole, ensuring it's nice and secure in there.
As I say, it's not recommended that you use this for anything other than a couple of seconds testing, however in my situation I'm using it as a permanent feature, and nothing's blown up yet :)