PSU powers up computer when just switched on (And keep everything powered on when shut down from windows)

[k-l-e]

Hi

I have a Corsair TX650 W PSU that's roughly 9 years old. For half a year now my PSU has been turning on my computer as soon as I switch the PSU on. It starts up fans, GPU, sound card, CPU. But it doesn't boot into windows until I click the power button on the case.

At the same time, If I turn my computer off in windows, it shuts down normally, but never turns off all components. I always have to switch the PSU power off to completely turn it all off. It does the same in sleep mode.

I tried to see what happened when I unplugged everything from the PSU, and once it's turned on, the fan starts spinning. Is this normal?

I've tried to take out the MB battery and reset bios. But nothing helps.
I just need to confirm if it's the PSU that's bad, or if it's my motherboard, which is fairly old aswell, Asus p8p67 LE.

 

[mortemas]

Sounds like the soft-off function on the PSU is latching. The OS request to shutdown goes to the point of fully closing out windows, but the psu won’t respond to the final request to cut power. Either that, or it’s the signal source at the mobo that is latched. If you have access to another PSU to test your computer it will tell you if the problem is with your PSU or with your mobo. Hmmm, maybe worth it to check the power button wires going to the mobo. Remove them from the mobo and carefully jump the pins on the mobo with a small screwdriver and see if the computer behaves like it should. If so, it could be a bad power button or a short in the wires leading to it.

 

[k-l-e]

I unplugged the power button wires from the MB, and it still happened. I also just tried to power on the PSU now with just a regular case fan connected. It powers the fan as soon as I switch the PSU on.

 

[smorizio]

check to see if your unit is under warranty if not i would replace it before it killed your rig.

 

[k-l-e]

check to see if your unit is under warranty if not i would replace it before it killed your rig.

Yeah it had a 7 year warranty so unfortunately I need to buy a new one. My GPU is already gone (So I think, might be the PSU here aswelll). I don't have a spare PSU to test with so I'll see with a new one.

 

[mortemas]

Yeah, the psu is stuck in the "on" state. The 20 pin connector has a pin that leads to the pins on the mobo where the power button plugs into. When you press the power button, it tells the PSU to provide power to the whole system. The power button is now irrelevant because the PS_ON pin on the psu (see pic below) is stuck to "always on" so that's why only the rear switch on the PSU can turn off your system.

 

[k-l-e]

Yeah, the psu is stuck in the "on" state. The 20 pin connector has a pin that leads to the pins on the mobo where the power button plugs into. When you press the power button, it tells the PSU to provide power to the whole system. The power button is now irrelevant because the PS_ON pin on the psu (see pic below) is stuck to "always on" so that's why only the rear switch on the PSU can turn off your system.

Then what explains that the PSU provides power to external components such as the fans when it's only the fans connected? Shouldn't it only start to power things once it'd get jump started?

 

[mortemas]

Yeah, that is the jump-start pin. To be clear, you totally disconnected the PSU from everything? ONLY a case fan was connected to it? If that's how you tested it and it powers the fan immediately then the jump-start pin is stuck on, even without a jump-start connection on it (paper clip trick). You need a new psu.

 

[k-l-e]

Yeah, that is the jump-start pin. To be clear, you totally disconnected the PSU from everything? ONLY a case fan was connected to it? If that's how you tested it and it powers the fan immediately then the jump-start pin is stuck on, even without a jump-start connection on it (paper clip trick). You need a new psu.

I see. Thanks for clearing that up. Well I guess it had a good run. I've been using it for a while in this state. But it doesn't seem to have damaged anything. Unless that's why my gpu died.

 

[mortemas]

Glad to help!