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Jumpering ATX Power Switch

Last response: in Components
May 1, 2003 3:14:06 PM

Hello All,

I want to know if it is ok to jumper the ATX power supply switch. I want to be able to turn on my computer by just switching on the power supply instead of having to switch on the power supply and then short the ATX power switch jumper. Is it ok to leave it jumpered/shorted all the time?


May 1, 2003 7:59:55 PM

I guess I don't fully understand what you're asking. Why not simply use the POWER button on your case? IMO, it's more troublesome to reach around to the back of my case to flip the PSU switch than it is to simply push the POWER button on the front of the case.
May 1, 2003 9:02:52 PM

Well I didn't want to get into details but I guess I'll have to. :-) We are using an ATX board for an "embedded" rack-mount based project and I don't want a "power" switch on the front as well as the back of the box. I'd rather just have the board power up when the power is turned on. If I could still find AT based boards I'd use them, but I can't. :-)

We use Linux and actually have been able to figure out a way to halt the system and this combined with the bios setting of having the power switch restore previous status makes it work. The problem is if the system is not shutdown properly it can sometimes get into the state where it wants the ATX power switch shorted and it is these times that are causing us the problem.

So, is it possible? Any other workarounds to have the board always power up when the power is turned on?

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May 2, 2003 12:38:18 PM

I have several power supplies that have been operating for over a year jumpered in the manner you are speaking of. From what I understand of the circuit it should make little difference to the life of your power supply if you ground the green wire instead of hooking up to the MOBO.

Any man can withstand adversity...The true test of character is to give a man power <i>Abraham Lincoln</i>
May 3, 2003 6:01:45 AM

To avoid anything BIOS might have to say about it, I'd simply ground the green wire to the case as Grub suggested. You can get "inline splicers" from Radio Shack that will avoid having to physically cut the green wire to ground it. Just use an inline splicer and a pigtail with a loop terminal.

<font color=blue>Watts mean squat if you don't have quality!</font color=blue>
May 3, 2003 10:51:34 AM

Leaving the green wire grounded works, at least to turn on the power supply, but shorting the ATX power switch doesn't work because the motherboard either won't turn on the power or will turn it off after a few seconds. Then there are some rare power supplies that won't turn on unless the green wire is grounded after the AC is applied. So instead of playing with the switch, it's better to just configure the BIOS to turn the computer on after any power failure.
May 3, 2003 8:16:17 PM

Before you go re-wiring anything look in your BIOS Power Management. Most have a setting for "After Power Loss" or "After AC Back" that lets you have the computer turn itself on when the AC power is restored.

But, there is a cotasil to this... Some "lesser brand" ATX power supplies are not designed to be turned off and back on all the time. They aren't designed to repeatedly handle the heavy startup surge of a total cold start. The intent is that the switch on the back should be used only as a service switch and routine startup and shutdown should be done by the software driven button on the front of the computer.

---><font color=green>It ain't better if it don't work</font color=green><---