How to power up ATX PSU without MB

I have an extra PSU lying around that I wish to utilize. Is there anyway to power it up without connecting it to a motherboard?

Thanks in advance.

you have to put a toggle switch on the power-on leads on the atx header, and maybe put a dummy load on the +5v.

see here for the atx pinouts and here for a dummy load example.

Usually 1/2 A is good for the dummy load, so 10 ohms should do it (5 ohms for a 1A if yours is stubborn)

@ merlin

Don't know, sounds dangerous. Post some pics of yourself after powering up with your tongue and I’ll consider trying it myself.

Since my main PSU is 350W and I have a spare 300W lying around I was thinking of powering the case fans and maybe HDDs(2) and optical drives (also 2) off the spare.

Main reason for trying this is my GF4200 is getting old and most new cards require a small nuclear reactor to power them
I don’t want to spend extra $$$ for a new PSU. Use the main PSU just to power the MB and video Card.

@rugger


Intel P4 (northwood) 1.8@2.6 Ghz
MB: Abit BD7II Raid
Ram: 2x512MB PC333 (2,2,5,2)
Video: GF4200 64MB (soon to be replaced)
HDD: IBM 120+80
Optical: DVDRW+CDRW
Other PCI stuff: sound blaster live, Firewire adapter, TV tuner, Winmodem
3 Case fans

It’s a wonder that my 350 Manages all of this.

Anyway I’m making a custom case (more of a hobby than anything else and not related to the PSU issue) therefore space is not a problem. Those PSUs might not be available here (St. Petersburg Russia) while there are good PSU’s available for 60-70$ (400-500w range) I really don’t want to spend money on that since I already have an extra PSU.

Got a 250W AT PSU too but cannot figure what to do with that. Any ideas?

having an external spare psu is good for testing fans, opening drives with cd's still inside etc.

Any other ideas or mods ?? I am sure there is something I can do with my 250W AT.

Expanding on DiscoDuck's mention, I have an AT power supply as benchtop tester similiar to this, is handy if you are into electronics.

@doolittle.

wow man that's just neat!!!!! I am into electronics (not hardcore just small projects repairs etc). This will be my next project after I finally finish(maybe hopefully ) finish my new case. I might not really need something like that too often but the task itself would be a nice reward. Should be easier with my AT PSU too.

At one time i was using my bench testing psu to power a really great set of 2.1 powered speakers for a pc, lost the power brick during a move. It provided ample 12v power to the speakers with the appropriate adapter connected to a molex connector. just had to turn it on manually with a switch under the desk to power up the speakers.

@DD - yea I feel your pain, I have made several AT bench PS and end up giving them away. I just spoke to a coworker yesterday and he needs one to power a dlink that needs 5v@2A, so there goes my current one (and my last spare AT power supply!)

I am thinking, I have a 20 to 24 pin ATX adaptor I am not using so I was going to fabricate it into a breadboard w/ the switch and banana plugs so I can plug into any ATX PS since there is no shortage of crappy units and what else do you do with the cheap PS that comes w/ the case?

But after some thought maybe I should splurge and get a 24 -> 20 pin ATX adaptor and use the 24 pin plug, so I can wire it for dual-rail so I will not have to upgrade when I get my dual-core breadboard