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How to turn a power supply "hard" on without motherboard?

Last response: in Components
August 19, 2007 11:53:17 PM

Does anyone know any good ways to make an ATX power supply turn on, via the case on/off switch, without a motherboard?

The reason I ask, is because I'd like to recycle a Case and PSU to be used as an external enclosure for 3 eSATA hard drives and 1 usb DVD drive... however, I'd like to not be limited to DVD/CD duplicator power supplies. I like my quiet Fortron ATX PSU. :) 

August 20, 2007 1:13:56 AM

you said hard on

August 20, 2007 2:05:20 AM

skittle said:
you said hard on


ahahahaha! beat me to it.
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August 20, 2007 5:02:34 AM

THanks, the hot wiring diagram may be helpful. I considered the duplicator case, but primarily I would like to use the ATX case PSU's, as they are highly superior (for the money) for quietness.

Also, I already own 2 extra ATX PSU's and 3 extra cases. It would be nice if I could simply mod an existing case/PSU to suit the needs of an external drive enclosure.

The daisy chain is actually a very good find. I could potentially daisy chain from one case to another, causing the drive enclosure to turn on and off whenever I turn off the computer (in theory.) - so that's worth looking into. However, I fear that this would cause both power supplies to try and power the motherboard. Also, I wonder if maybe running sata power to the next case, with an external connect/release point might be a good, cost-effective choice.

THose AT-style PSU's are noisy and have small fans. I try to only use slowish fans 120mm and up, as I am a freak for silent operation. I was hoping there was an easy way to hook the ATX PSU up to the case power button. Somebody should design a little motherboard that serves that purpose, but doesnt have any processors or even a northbridge.

a b ) Power supply
a b V Motherboard
June 10, 2009 3:27:58 PM

to turn on a psu without a motherboard you need to short out the green wire to any black (earth) wire with some solder or a paper clip
June 10, 2009 4:07:02 PM

If you dont have a load on it (cd-rom,floppy drive etc) it may not turn on at all.
If you havent already put a load on it then try that.
November 29, 2009 12:17:57 PM

to turn on a psu without a motherboard you need to short out the green wire to any black (earth) wire with some solder or a paper clip

Hi, when you said 'short' does it mean connect it for second and then release or stick it there as long as you wanna use it?

November 29, 2009 12:40:02 PM

Got the answer. Tq. just short it and release. don't leave the paper clip there.

a b ) Power supply
a b V Motherboard
December 10, 2009 7:48:57 PM

If you have a motherboard connected, just a momentary short. If not, you need a permanent short like a on/off switch.
a b ) Power supply
a b V Motherboard
December 11, 2009 3:56:07 PM

You'll need to short green pin to any black pin. That will turn on your PC. To supply power continuously this needs to be connected all time.

Here is the pin out:

I use a cheap Antec Basiq as a lab PSU to power some of my robotics stuff. The +5,+12 rails really come in handy for testing stuff.
December 17, 2009 12:33:51 PM

Just shot the green and black wire on the 24pin connector with a wirre or anything else!
December 17, 2009 12:45:50 PM

Hmm obviously the psu is turned on by signals coming from the motherboard but im not sure?.
a c 144 ) Power supply
a c 156 V Motherboard
December 17, 2009 1:37:29 PM

This started as a resurrected two year old thread.

brendz: Only indirectly. The case power switch is tied to the green PSU wire through the motherboard on one side and ground on the other. So pressing the case power switch does the same thing as the paperclip trick of shorting the green and a black wire together.