How to Power Up an ATX Power Supply Without a PC!




Introduction: How to Power Up an ATX Power Supply Without a PC!

In this instructable i will show you how to power up an ATX Power Supply without a PC.

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!

Just look after the green wire in the cable tree from the PSU.
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!

Now it's time for the wire.
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!

2 Notes:

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

Add a switch instead the wire!

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....

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111 Discussions

EdwinM73 thank you SO much! Superb advice regarding the brown wire. I've been struggling with this problem for some time now, so the power supply went off suddenly since I wasn't using the brown wire! Now it works perfectly by following your advice!

You missed something important for 24 pin PSU,s. i bet many had tried this and had their PSU just turn on for a second then turn off, If you have a 24 pin psu you MUST connect the brown cable to an orange cable "brown is the voltage sense" and the green to black ! Your 24 pin psu will now work as intended standing alone. Additionally for stable and correct voltage you should also have your psu under 10% of its rated load from startup, i.e. if you have a 750watt psu you should have 75 watts of load minimum, you can just use a Panel Mount Fixed Resistor say 50 to 100 watts, again the psu will turn on with out load but may not give the exact voltages you desire. Hope i helped you all : )

2 replies

Hi Edwin,

I am also running into the same problem and landed on your response here in regards to connecting the brown to an orange connector. So I have tried this, and still the PSU will turn off as soon as I put load on the 12v 4pin connectors. One thing different though is that my pin #13, is actually brown and orange. There is two wires going to the pin. What does this mean? Does this work differently?

The pin #13 will be the orange already connected to the brown, nothing to do there. If you have connected the green to a black and it still doesn't work, try adding a small load (12v headlamp etc).

If that doesn't work, maybe you have a dead PSU


I use this method to power my LiPo charger from an ATX supply also but if you want to get more juice from the 12v output than you need to load/stress the 5v output on it, otherwise can't give much Amps. Sorry for my bad english! So I ended up put a 12v 50w light bulb that used in cars attached to the 5v line (You can use a ceramic resistor too but with heatsink). Without the bulb my charger capacity was only 2,5-3Amps, with the bulb I can charge up to 6Amps. I hope it helps stg!

Please help me!! When I connect black with green. It starts with a jerk and then turns off.. What is wrong with that ?

4 replies

The power supply probably needs to see some kind of load. Try hooking up an old cooling fan from a old case as a load.

or do a google your power suppy followed by 24 pin pinout

are u using a button looks like u need a switch or just wire so try a switch itll probally work tho dunno what else to say

I have the same problem, you already fix there?

I use an ATX by Cooler Master (V1000)

Thank you!

Hey everyone,

I followed this guide and connected my Arduino on the 5V and a 12V small motor on the 12V. This worked perfectly, but when I tried to connect a bigger motor (a windshield wiper motor) to my ATX, it didn't work. The ATX generates about 22 amps so it should be working! Does anyone know how this is possible?

Thank you!

1 reply

Have you verified the windshield motor to be good with either a meter or another power source?

for those of you who are lucky enough like me to have a power switch behind the psu, and that you wish to dedicate it to experiments, what i did is cut the green wire and a ground close to the psu case, soldered and insulated them together, you can then just use the switch behind to power it on/off!!

So after doing this, is it possible to run a hard disk (old 4pin socket HDD ) continuously by plugging it to the power supply, so that I can use it as a make-shift grinder ?

1 reply

If you haven't found your answer yet, (this is a couple month old question...), on my ATX Power block, most of the cables are labeled with the Voltage (on the board itself), However, the green wire is, at least on mine labeled "Remote".

If you've figured it out just disregard my mssg, but if you have yet to find an answer, look on the board for a "Through Hole" Labeled "Remote", that's the Green +5V line. Hope that helps.


1 year ago

i am planning to use this in my pc. is it okay to power a hard drive using this? because i will connect two psus to an avr, so when i switched the avr on, the wired psu will turn on. will it be okay that the hard drive is powered while the motherboard is not?

Thanks Mate, I really appreciate your sharing

Without looking at any vids or other I had the idea of using the power supply from an old PC. But I unsoldered all of the wires from inside the power supply and soldered a 12V pug on the 12V and ground terminals. but it does not work. So Ithink i need to solder a wire from wherever the green wire connects to ground inside the power supply. Can you help?