Multiple PSUs

[angusb]

I was planning to run a second power supply in my system to power the fans, lights, etc. The plan was to just jump pins 14-15 on the second supply as I know this will turn on a ATX power supply. I would then plug its 110v input into the switched 110v power outlet on the primary power supply (Vantec 470). So when the main supply came on the second would automatically turn on as well.

However, I recently read something on a page saying that jumping the 14 pin for extended periods was bad for the power supply and could burn it out eventually. It stated something about that while jumping pins 14-15 will start the supply up, that normally the motherboard does not simply jump them but there is some kind of load/resistance or something on it.

I have opened up two power supply testers and found both simply jump the 14 pin to turn on the supply, however, both also state on the package that running the psu connected to the testers for an extended period could damage the psu.

I cannot find any more info on this one way or the other. Does anyone run a supply in this manner for extended periods? Anyone know the the truth?

 

[Crashman]

I'd connect the green wires together. You can do that with a tap type splicer.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[angusb]

Thank you for your thought.
I am aware that jumping the 14 (green) wire to a ground wire will turn on the power supply. I'm trying to find out if it safe to do so. I have read opinions that it is not safe to do so for long periods due to some missing load/resistance that is normal introduced by the mother board, and the warning on the supply testers does seem to back that up.

My question was actually if anyone has been running a second supply in this way for any length of time.

 

[Crashman]

No, I'm saying connect the first power supply normally to the board, and connect the green wire from the second supply to that of the first. The motherboard should be able to switch on both power supplies simultaniously.

Radio shack as well as auto parts stores have inline splices that can bridge the wires together without cutting them (they only nick the insulation).

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[angusb]

Thank you. I did understand, its just that I am not looking for how to do it, I am asking if 1) it is safe to do it(as I read it is not for long periods), and 2) has anyone actually been doing it for an extended period.

So far my feeling has been that it is safe, despite the hints that is may not be. However... here is another bump in the road. I emailed my power supplies manufacturer about this and this is the response I got:

"Running a ATX power supply by connecting the #14 pin to one of the ground wires can significantly shorten the life of the unit. It can also cause the unit to output unstable power levels on any or all lines over time. The same can be true of connecting the #14 pins and ground pins of two power supplies to the same motherboard connector. This is due to the unique power level relationship of the motherboard and power supply, the motherboard does not simply ground the #14 pin to one of the power supplies ground wires. Needless to say this will also void your warranty."

So I don't know if it is true, but I can't see why they would lie to me about it, but now I can certainly see why others would think it was possibly unsafe with a manufacturer saying it. I guess I will need to actually go get a multi-meter and try some tests with a board I don't care much about poking with the power on.

 

[Crashman]

Yes, well, I was just saying that since you're not connecting the second #14 directly to ground, but instead through the motherboard's #14, if there is any resistance added to that circuit it should be enough for both circuits. Anyway, the only problem I can see here is the unloaded 3.3v line on the second power supply. You could of course use it for something!

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>