[SOLVED] Possibly fried motherboard or problematic PSU

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blackburnman04

Honorable
Sep 16, 2015
15
0
10,510
Hi all,

I built a small machine with the following specs

CPU: Ryzen 3 3200G
Cooler: 120mm CPU Fan from Amazon - can't recall the brand
SSD: Sandisk Ultra 2 - 256GB
M.2 Drive: Western Digital SN520 - 128GB
No GPU - On board graphics
PSU: Aerocool Cylon 600W
Motherboard: MSI B450 Pro Max M2


Everything had been working fine, until I purchased a HDMI monitor today (I was currently using a VGA monitor). I connected the HDMI cable to the new monitor then to the slot on my motherboard. The screen showed successfully but I noticed that I was unable to move my USB mouse, or type on my keyboard. I thought I would try a reboot of the machine. After rebooting there is now no display showing on the monitor and when I plug any devices into the USB ports on the front or back of the machine, e.g. my Keyboard, there are no lights showing on it (e.g if I press the numlock key).

Things I have tried:

I tried connecting the previous monitor via the VGA port on the motherboard (removing the HDMI that was currently connected ) - issue persists.
Tried to clear CMOS by removing battery and clearing JBAT1 jumper - issue persists.
Tried to connect computer to my TV via HDMI port - issue persists.
Reseated CPU - issue persists
Tried one RAM chip at a time in different ports - issue persists
Disconnected CPU power cable and 24 pin ATX power cable from motherboard and reconnected - issue persists.
I tried different VGA and HDMI cables each time as well.

Strangely the EZ Debug LED shows white for a second (solid) when machine is turned on, but after this point no lights are showing, but fans and lights on front of case showing without issue, but there are no USB devices working and no display being detected.
When I initially plug in a HDMI or VGA cable, the monitor light will stay solid, as if it has detected the computer, but then it just flashes and states No display found.

I would be extremely grateful if anyone could provide guidance on what this may be. Would it be likely the motherboard of PSU could be fried by just plugging a HDMI cable into the slot on the motherboard?

Many thanks,
Brendan
 
Last edited:
Solution
Sounds like a 5V failure on the power supply, not getting any voltage out of the USB ports is a good indicator of that.

Also a computer will stay on when 5V fails, the mouse can even be moved since that is 100% hardware to the CPU, and it runs on 12V.

As to why, maybe a little ESD (static electricity) or ground loop problem when you plugged in the HDMI cable caused OVP to trip. And being a cheap PSU, might have just failed open and won't recover itself.

kgabris

Prominent
Apr 5, 2020
27
2
535
just woo me off, if im talking stupid, but (of course I suspect where it is), but the parameter memory of the jumper perhaps could be converted to a different format? to save memory? whynot? what could go wrong?
you never know... I mean, 4kbts is too much for binary.... hexa is always unstable...