Is signal on motherboard preventing powerup?

[jerrymiller0]

Gateway decktop PC, would not power up at all. After some troubleshooting I cut the green wire to the 24 pin power supply connector and added a switch to ground, and between using that and the power switch I am able to start up/shut down the PC, and everything works fine. But, if I unplug the power supply from the wall for more than about 30 seconds and plug it back in, I can't get any power at all using the green wire or power switch, until I remove the 24 pin power connector from the motherboard momentarily, then it starts up/shuts down fine as long as the power supply remains plugged into the wall. Is there a signal on a wire other than the green
wire on the connector that can prevent the power supply from turning on? I don't want to replace the power supply or motherboard since the PC works fine when its on, but if there is a signal interfering with the power supply I could add another switch instead of having to open up the PC and remove and replace the connector.

 

[akseli]

So, when and how did this problem start?

I think, if the BIOS reset pins are connected, then the system would not boot until they are disconnected.

Typically there are two pins for that and might be also a separate buttom on board for that. Maybe you have installed the different front panel switches and leds incorrectly, and connected that.

 

[jerrymiller0]

So, when and how did this problem start?

I think, if the BIOS reset pins are connected, then the system would not boot until they are disconnected.

Typically there are two pins for that and might be also a separate buttom on board for that. Maybe you have installed the different front panel switches and leds incorrectly, and connected that.

 

[jerrymiller0]

The PC was working fine a month or two ago. I had not turned it on again until recently and it would not power up. Maybe there was a power surge due to thunderstorms. I hadn't done anything inside the PC until after the problem. The power switch and led seem to be working correctly (except that I have to operate the green wire to the power supply manually). The PC boots up and down fine and windows 10 works, as long as the 115VAC is not interrrupted. I can leave the PC off overnight and it will still boot up in the morning. But if I unplug it from the 115VAC for a minute while the PC is off, I can't power it up again the first time without disconnecting the power supply to motherboard connector momentarily.

 

[akseli]

Yes, I thought that if you'd have done some installation it to, then some misplaced wires could be a cause, but since you haven't, that can be ruled out.

Power surges shouldn't matter much if the computer was off. Whatever little power the computer takes when off, I think it's unlikely to cause any damage. Direct lighting strike into the house or nearby wire is a different thing.

Maybe as the computer is old, it could be battery, or capacitors on the motherboard or power supply. Over age some capacitors tend to leak or bulge. Typically the computer may still work fine when it boots it, but it may have problem starting up cold, or warm.

If the system doesn't boot after a brief dissonnect of power, then try to start the computer with power disconnected from wall. That will drain empty most capacitors and worn out capacitors recharge better when they are completely empty, so it the computer then boots up consistently after first draining them out and then connecting the power, I would suspect capacitors.

If not, try replacing battery.

It could be something else too. Your switch trick doesn't perfectly fit the problem if it would be worn out capacitors, as it shouldn't have any effect, and obviously it has.