# How do I force a PSU to turn on?



## audiobahn1000 (Sep 2, 2006)

I have a 550 watt PSU I got with my case.  I want to use it to power some 12VDC lights that will go around my computer.  However when I plug it in and turn on the switch in the back of the unit, it does not turn on.  So apparently its waiting from a signal from the mobo that is not connected for it to turn on.  Well how do I force it to turn on?


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## Burgerbob (Sep 2, 2006)

It is most likely a dead PSU, the PSU doesnt wait for a signal from the mobo to turn on. Try a different one and see if it works.


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## PC eye (Sep 2, 2006)

Burgerbob said:


> It is most likely a dead PSU, the PSU doesnt wait for a signal from the mobo to turn on. Try a different one and see if it works.


 
 That depends on what connector you are using. The main 20 or 24pin connector will be lifeless until the power switch is pressed. Power isn't send out to the drives until the system is powered on. Fans don't run unless the power is turned on. The auxillery 12v feed is the only active feed with the remaining connectors plugged into the board itself.
 (Gee? when I unplugged the mouse from the usb port and plugged it into the PS2 socket the system suddenly powered up this morning. I think that had to do with power on with any key enabled in the bios.)


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## Burgerbob (Sep 2, 2006)

PC eye said:


> That depends on what connector you are using. The main 20 or 24pin connector will be lifeless until the power switch is pressed. Power isn't send out to the drives until the system is powered on. Fans don't run unless the power is turned on. The auxillery 12v feed is the only active feed with the remaining connectors plugged into the board itself.
> *(Gee? when I unplugged the mouse from the usb port and plugged it into the PS2 socket the system suddenly powered up this morning. I think that had to do with power on with any key enabled in the bios.)*



Ive scared the crap out of myself when i accidentaly had Power On PS/2 Mouse enabled in BIOS, i kept hitting the mouse on accident and it would power on... finally figured it out half an hour later. Also, he said that he had hit the power switch in back of the PSU... what else could he do? mobos with the 24-pin connector will still work with only the 20-pin.


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## PC eye (Sep 2, 2006)

You may get a board to start with the 4pin plug separated. But try using a supply with a 20pin connector. When trying an Antec TP II 430w supply on this board it won't startup. Of course that may have been the time the wires for the power switch lifted off of the pins while getting ready to start the new build up for the first time(oops!).

The possible way to have everything work there would be to have the lights connected into a molex plug for the auxillery 12v feed with a switch in line. When you start the system you throw on the switch. You wouldn't be tieing up any of the connectors coming directly off of the supply there. Of course that would pull more power through the board heating it up more.  !

 Have an extra old supply hanging around with no use? Another thing to look at is how the lighting will be setup. What types of lighting are being used? An external ac to 12v converter would avoid any wires hanging out of a case.


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## diduknowthat (Sep 2, 2006)

You take a little paper clip or anything metallic, stick one end on the green cable of the 20 or 24 pin connector, and the other end in the black cable of the connector. This should "jump" start your psu without connecting it to the motherboard.


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## SirKenin (Sep 2, 2006)

Man, I don't know where people get their information from.  I think it's from "High Times" while they are smoking some wacky tobaccy...

An ATX powersupply does in fact wait for a signal from the motherboard to turn on.  That's the whole point.  That's how they work.  Powerswitch to mobo, mobo to PSU.  Without that signal, the PSU will not fire up.  However, if you short pins 15 and 16 on a 24pin PSU you will get it to turn on (green and black).

Man alive... lol


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## PC eye (Sep 2, 2006)

SirKenin said:


> Man, I don't know where people get their information from. I think it's from "High Times" while they are smoking some wacky tobaccy...
> 
> An ATX powersupply does in fact wait for a signal from the motherboard to turn on. That's the whole point. That's how they work. Powerswitch to mobo, mobo to PSU. Without that signal, the PSU will not fire up. However, if you short pins 15 and 16 on a 24pin PSU you will get it to turn on (green and black).
> 
> Man alive... lol


 
 I guess they haven't figured that one out yet. If you are going to start jumping pins in a connector you might as well want to use an old supply separate from the case itself and splice a toggle switch in. With a connector down into the main on the board would you splice wires there?  ! This is why I was asking about the type of lights intended for use there. One haphazard wiring job will make more of a mess.


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## diduknowthat (Sep 2, 2006)

PC eye said:


> I guess they haven't figured that one out yet. If you are going to start jumping pins in a connector you might as well want to use an old supply separate from the case itself and splice a toggle switch in. With a connector down into the main on the board would you splice wires there?  ! This is why I was asking about the type of lights intended for use there. One haphazard wiring job will make more of a mess.



I think he just wants to run the lights off the 550 PSU that he got from the case, though i don't see why the light can't just be ran off the main psu..


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## PC eye (Sep 3, 2006)

The point was about trying run to run the lights without the system itself going. That would be a little out of the question unless there was an auxillery 12v molex socket available. You would find that in the gap between the video card and the rear panel. For llighting things up without starting the system an external 12v source would be the thing to look at.


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