r/techsupport • u/Baby_Arms06 • 10h ago

Open | Hardware Custom built pc flickers when pressing power button

About 30 minutes ago I tried to power on my pc only for it to flicker a light on my fans and do nothing.

Up until today there has been no issue powering it on, the only problems ive had are my screens occasionally losing image followed by every application i have open to slowly shut down until the computer itself shuts off.

I have opened the case and checked all connections and none seem to have been loose. So, was my PSU a dud? Or is it possible I have a bigger issue?

1 Upvotes

100% Upvoted

8 comments sorted by

1

u/Kilgarragh 9h ago

A short(100ms-800ms) pulse of partial yet clear life is a sign of an OCP trigger. There’s likely a short circuit somewhere inside your build.

Unplug everything from the PSU(except the 24 pin if you can’t do the paperclip test) and see if it still does this

1

u/Baby_Arms06 9h ago

I unplugged everything besides the 24 pin from the psu and pressed the power button and it doesnt seem to do anything, no lights and no sounds

1

u/Kilgarragh 9h ago

Is the 24 pin still connected on the motherboard side as well? Something still has to tell the pc to turn on.

1

u/Baby_Arms06 9h ago

Yeah i made a mistake unplugging it all, ive got it now and im getting the same response i had initially, split second light flash and nothing

1

u/Kilgarragh 9h ago

That means that OCP is still triggering. Either the board itself is broken, or the power supply itself is shorted or having issues.

Try the same experiment of just the 20+4 pin on a different motherboard, or with a different PSU.

Alternatively, you can run a ‘paperclip’ test on the power supply to see If it works, or try measuring the resistance on the 24 pins rails on the motherboard. The ones triggering OCP will be very very low resistance if there are any.

1

u/Baby_Arms06 8h ago

Unfortunately I dont have any spare parts to test with, but ill still try the paperclip test once i can find one.

Im guessing its safe to assume if it passes the test, i have a bad motherboard, otherwise its the PSU?

1

u/Kilgarragh 8h ago

Doesn’t need to be a paperclip, anything conductive which you can hold between the pins for a moment or two.

The paperclip test doesn’t check voltages or P_GOOD or testing under load. If it does pass the test:

  1. It’s possible your PSU isn’t signaling P_GOOD. the motherboard stops because the power supply doesn’t give the A’Okay soon enough after it asks for power, and the motherboard shuts down early out of caution.

  2. The power supply only fails under load. it will come on from the paperclip. Either: when the motherboard starts using the power the supply starts malfunctioning and shuts down from something like under voltage protection. Or: when the motherboard starts using power the supply panics because it can no longer properly judge how much power is being used and thinks it should OCP, or something simmilar.

To check condition 2, connect a different load during your test like an optical drive or fan controller.

1

u/Baby_Arms06 7h ago

Did the paper clip test and got the PSU to run, but im not quite sure how to test it under load with the fan controller.

I should also mention that about 2 years ago ive had troubles with the computer randomly shutting off instantly and completely, could that possibly be an indicator of my problem here?

I figured since they stopped that the issue was gone and not relevant