Question Hardware Failure

Jul 30, 2021
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Hello all,

This is a strange one! I inadvertently plugged-in a usb 3.1 hub into the rear HDMI slot ( yes not good ). It crackled so I powered-down. Now it boots intermittently; most of the time, it won't boot. There are no fans, no beeps, nothing. If I remove all the cables and wait, it boots. When it does boot, everything runs flawlessly. My thinking is power supply misbehaving at boot although, as mentioned, no sign in use. If the motherboard was damaged, surely it wouldn't work at all. My thinking is power supply. If it were bios or something, there would be something but there's no sign of life at all until it decides to boot. It has me stumped: I don't want to replace anything unless I know the culprit. Any thoughts regarding this please?


Z390M
i5 9600k
16GB DDR4 2666
Corsair CV650
Sapphire RX5600Xt
Windows 10

Pete
 

Ralston18

Titan
Moderator
The connection error likely caused a short circuit in either the cable and/or port.

Try other known working cables. Hopefully the problem is just a short inside one of the cable plugs.

Is that USB hub independently powered or does it rely on host computer USB power? How many USB devices are connected to the hub?

Take a close look at the affected port(s) and adjacent ports as well. Inside and out - both ports and case. Use a bright flashlight to look for signs of damage. Bare conductor showing, melted insulation, browned or blackened components. Physical damage of any sort.

Booting up being intermittent does indeed make troubleshooting more difficult.

Remember that motherboards use three different voltages (3,5, and 12 volts) via different "rails". So a problem with or the loss of one voltage can occur while the remaining voltages make the motherboard and supported components appear to be working.

If you have a multi-meter and know how to use it you can do some limited testing on the PSU:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test as the PSU is not under load. However any voltages out of tolerance indicate a problem PSU.

You may be able to test the cables for continuity as well. For the most part just swapping in a known working cable is simpler and likely to be more conclusive.
 
Jul 30, 2021
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I installed my son's psu and it's booting every time so far. Fingers crossed this is the solution. It's the HDMI socket on the io on the motherboard
 
Jul 30, 2021
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Interestingly, however it is now saying usb devices failing: port reset failure. Not sure if this is relevant or I've put the usb devices back in different slots
 
Jul 30, 2021
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It appears that the psu is the culprit. I'm not having the intermittent boot now. It's interesting to learn about how to diagnose these things: I didn't know about the 'rails' and the different voltages. It's all a learning process. It might be the case that the psu was on the way-out anyway and this the catalyst. Thanks for your input chaps
 

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