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Possible to run PSU by itself?

G

Goi

Diamond Member
Hi,
I'm wondering if it's possible to run an ATX PSU by itself without a motherboard/case? I know I can jump 2 wires(can't remember which ones though) on the ATX motherboard power cable but I also seem to remember that the PSU requires a motherboard to be present due to its regulation circuitry, and that running it without a motherboard would damage the PSU. I wish to use a PSU somewhere else just to power a few fans. Would that work?
 
You connect the green wire with a black one. Its best to have something plugged into the PS though, such as a HD; many have a minimum draw that is required on each rail for them to run.
 
Would it be possible to just use some resistors as loads for the +5V and +12V rails, in addition to the fans I will be driving? If so, what kind of resistances am I looking at?
 
Hey Goi,

Somebody had a site with this same project. I thought I kept a link, but can't find it now. Might play around with google and see if you can find it.

Fern

Edit: Try this Link. Although in re-reading your post, not sure it's what your looking for
 
I'm running two power supplies in my system, and one power supply is shorted to a switch, so that when I hit the switch in the front of the case, it turns on the power supply. That power supply powers 4 hard drivers, and all 12 fans in the case. Haven't had any problems with it at all...
Tas
 
Hmm, I'm just wondering what kind of load the PSU expects when not connected to a motherboard. Thanks for the pin info Kensai.

I'm trying to run the PSU standalone, not as a relay connected to another PSU.
 
Thanks. Now that I know which pins to jump, can anyone tell me what kind of loads I need to put on the +5V and +12V rails to prevent the PSU from frying itself? Can I just put a few 100K resistors there or something, or does it require a higher current load?
 
You can just use an older psu like from a 286. They don't have to be jumpered and would be perfect for your application
 
Yeah - I'm sure someone here has an old AT PSU that is doing nothing usefull that you could get for the cost of shipping. Would be a much better solution than to jumper an ATX PSU.
 
Well, I already have an extra 250W ATX PSU that's lying around doing nothing so I would like to use that if possible.
 
Well, I think that for my Antec PSU you need a minimum load of 0.8A across the +12V. So, if my sums are right, you would need a 15 Ohm, 10W resistor. But if you make sure you always have 0.8A 12V load (Fans/Cathodes etc...) you should be okay. Im not sure though, never having tried it myself.

RoD
 
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