Question PC on black screen and doesnt 't turn off.

[Omarrr128]

I was changing a usb cable whilst my pc was on for my AIO so I could control the RGB and I heard like a click elsewhere in my pc and my screen went black.

I had to turn it off from mains to get it to turn off.

When I press power button all the fans and rgb work but screen stays black and monitor detects nothing.

Pressing power button doesn't make it turn off.

QLED doesnt show any lights either.

I've taken out mobo battery and checked psu cables but they seem to be fine.

I reseated ram sticks. The rgb for them works as well. They seem okay.

Not sure what problem is?

 

[DRagor]

I was changing a usb cable whilst my pc was on for my AIO so I could control the RGB

You mean the cable that connects AIO to USB header on motherboard? While PC was running?

 

[dfflick]

The click elsewhere in your system was probably a motherboard short because you decided to mess with mobo cabling with the PC on.

 

[Omarrr128]

You mean the cable that connects AIO to USB header on motherboard? While PC was running?

Not to the motherboard the one that goes to the back. I know it sounds bad but I've done it a few times without problems. The Aio screen wasn't working and I had spent hours booting it on and off. Would this have damaged the motherboard or something else?

 

[DRagor]

Not to the motherboard the one that goes to the back

Please list your motherboard and AIO model so we both speak about same things.

 

[Omarrr128]

Please list your motherboard and AIO model so we both speak about same things.

AIO is kraken z63
Mobo is asus b450f rog strix.

I plugged the cable from the Aio into the usb port on the side of the pc. Where you wud put normal usbs. Not the usb header on the mobo.

If I did short circuit the mobo then does it power on and allow the fans and rgb to work? QLED however doesn't work.

 

[DRagor]

I plugged the cable from the Aio into the usb port on the side of the pc. Where you wud put normal usbs. Not the usb header on the mobo.

Ok, now I have a clear picture. It's not as bad as using header on mobo, but still dangerous. Normal USB device are not powered when you are trying to connect them so even if they short with case nothing happens. But AIO while running is powered, so if your case was not properly grounded it could certainly cause short when trying to connect it. Yeah, it worked few times fine, but that does not mean it's safe thing to do.

If I did short circuit the mobo then does it power on and allow the fans and rgb to work? QLED however doesn't work.

It is possible.

The Aio screen wasn't working and I had spent hours booting it on and off. Would this have damaged the motherboard or something else?

It could happen but not very likely.

Most likely mobo is damaged. There is slight chance however that's it's AIO that failed and it stops system from booting. So I would first replace AIO with air cooler (any will do since that's just test) and see if it changes behavior.
Btw, what happens now when you turn on PSU switch? Is it normal behavior or something weird? Because it could be PSU that was shorted instead of mobo.

 

[Omarrr128]

Ok, now I have a clear picture. It's not as bad as using header on mobo, but still dangerous. Normal USB device are not powered when you are trying to connect them so even if they short with case nothing happens. But AIO while running is powered, so if your case was not properly grounded it could certainly cause short when trying to connect it. Yeah, it worked few times fine, but that does not mean it's safe thing to do.

It is possible.

It could happen but not very likely.

Most likely mobo is damaged. There is slight chance however that's it's AIO that failed and it stops system from booting. So I would first replace AIO with air cooler (any will do since that's just test) and see if it changes behavior.
Btw, what happens now when you turn on PSU switch? Is it normal behavior or something weird? Because it could be PSU that was shorted instead of mobo.

Thank you for your reply.

The psu acts as normal from what I can see. I turn psu on and the mobo Rog logo light comes on like normal.

When I press the boot buttom the screen of the AIO does come on like normal. I will swap it with another one and get back to you to see if there's any difference.

I did have issues with my previous AIO where it didn't work properly and it wud say CPU fan error at start up. Surely if it was the AIO it would come up with an error rather than just a black screen?

 

[DRagor]

I did have issues with my previous AIO where it didn't work properly and it wud say CPU fan error at start up

Well, that error pops up if nothing's connected to CPU_FAN header (and many AIOs don't connect anything there), so that's normal.

Surely if it was the AIO it would come up with an error rather than just a black screen?

Depends on the problem. A short on the pump circuit could cause start problem while everything else on AIO could work just fine.

 

[Omarrr128]

Well, that error pops up if nothing's connected to CPU_FAN header (and many AIOs don't connect anything there), so that's normal.

Depends on the problem. A short on the pump circuit could cause start problem while everything else on AIO could work just fine.

I changed to a stock amd cpu fan. Unfortunately nothings changed. I think it's either cpu or mobo. How would I tell which one it is?

 

[DRagor]

I think it's either cpu or mobo. How would I tell which one it is?

Well, you can't. Not without having access to replacement part, which usually is not possible as most people don't have spare mobo lying around.