This story involves:

  • 3 monitors with HDMI ports (1 is actually a TV, none are connected to any network)
  • 5 computers with HDMI ports (1 with Linux, the others with Windows 10)
  • 4 HDMI cables

All of which are in a visibly-perfect shape.

The story started with 1 monitor failing to receive video signal from 1 computer. You know the drill, time to isolate the problem by trying different combinations of (monitor, computer, cable), swapping out 1 element at a time. Boooring...

First surprise: there was no clear, isolated culprit, as each monitor/computer/cable was involved in at least 1 working combination. Let's try again some of the combinations, to clear out potential false negatives, surely I've made a mistake somewhere.

Second surprise: some combinations that worked during 1st attempt, don't work anymore during 2nd attempt. Wow, looking for false negatives, finding false positives. Can HDMI failure really propagate from device to device ?!

Turns out it did. I stubbornly retried combinations, refusing to acknowledge the possibility of an issue that propagates. Soon enough, no combinations worked anymore. At this point, just a couple of hours have passed since this story began... that escalated quickly !

Some of the devices have another video connector available (VGA or DisplayPort), which still works perfectly. But for all of them, HDMI invariably fails to work: devices don't even acknowledge the presence of a plugged-in HDMI cable with a device at the other end.

The only theories I can imagine to explain this propagation behavior are:

  • a faulty device overloads HDMI cables, which melt down (internally, without externally-visible trace ?) and stop working
  • a faulty device overloads the HDMI controller at the other end of the HDMI cable, burns some of its components, which effectively breaks it

They both seem far-fetched and, as a good citizen, I can't fathom the idea that an actual software virus went through HDMI cables. I am apalled at what just happened, have no idea how to progress and am afraid of borrowing a friend's monitor/cable/computer to make further experiments, lest I would break their precious equipment.

Do you have any idea what could explain this, and how to fix it ?

  • What operating system(s)? Was some software or the OS updated when it happened? What is common between the 5 computers and 3 monitors?
    – harrymc
    Feb 16 at 20:18
  • 2
    Were any device equipped with 2-pole ungrounded mains plug, or equipped wih 3-pole grounded mains plug, but connected to 2-pole ungrounded socket? And you hot-plugged HDMI when one or more devices were connected to mains but ungrounded?
    – Justme
    Feb 16 at 20:28
  • 1
    @koral You might want to check the manual if it warns about not to do any connections unless the mains plug is disconnected first. Most 2-prong consumer devices have that warning in the manual to prevent damage when doing connections. Long story short, there might be voltage difference between the two devices, and if it equalizes via data pin instead of connector shell, it can damage devices. Sometimes the voltage difference is large enough that it hurts a bit when touching two devices.
    – Justme
    Feb 16 at 20:50
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    @koral, have you tried shutting all devices, PC's (full shutdown/restart) and monitors, unplugging them for a few minutes, and then plugging each into grounded outlets and PC-to-monitor HDMI, then rebooting and turning on monitors? Also, try following the monitor reset sequence. If that doesn't work, as others have surmised, likely HDMI port hardware has been damaged. Feb 16 at 21:14
  • 1
    Consider replacing your HDMI cables too, it could be the DVI virus evolved. It's a fictionalized story, but you get the idea. By the way, a skilled technician could be able to replace a HDMI port if it's a mechanical failure.
    – gronostaj
    Feb 19 at 7:48

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