I had a similar problem.
Several similar problems to be correct.
I also have a NVIDIA card (ASUS laptop). 

The first time around was the TV/laptop combination.
It just didn't want to work. 

So I got another TV.
Which didn't work either...
Until I replaced the HDMI cable for a better quality. 

I could not make it wort with Mint (can't remember the version) so I went 
with Ubuntu.
Until I upgraded Ubuntu...
Then Linux Mint worked flawlessly.
Until I upgraded it to 18.2 

After a bloody battle I made it work.
For the most part... 

Until I upgraded to 18.3...
Now we are in a stalemate, where it works most of the time as expected.
Until I *TOUCH* the connector to the laptop.
Then the song and dance begins again...
I haven't had to go so far as to replace the drivers (this time) but I can 
relate very well to your horror story.
At this stage I don't know if have a weak connector, a flimsy cable, a 
cantankerous TV or I am just down in my psychotic medication and I am 
imaging the whole thing, but I have fences, and I don't breath, around that 
%$#@ connector. 

I hope this helps, but if it doesn't, I can forward you the contact 
information of my therapist.
He doesn't know anything about HDMI, but prescribes very yummy gummies...
:)
ET 


Jim writes: 

> I have a box running kubuntu 18.04 64 bit and an NVIDIA Geforcee GT520 
> video card.  The first monitor is connected via the DVI connector.  The 
> second monitor using the HDMI connector. I also use the  second monitor 
> for the cable box and I have an hdmi switch to connect the second monitor 
> to the computer or the cable box. 
> 
> The problem is that the computer doesn't recognize there's an hdmi monitor 
> connected.  Sometimes it does this when I boot up the machine.  
> Sometimes when I have the second monitor connected to the cable box and 
> switch back to the computer, I don't get the second display.  If I'm 
> lucky, restarting the x server will work. Sometimes I have to reboot the 
> machine.  If it really wants to be a pain in the ass, I have to uninstall 
> the NVIDIA drivers, and restart the x server.  Then the Nouveau drivers 
> are used and it works.  That is, until the next time it happens and 
> reinstalling the NVIDIA drivers fixes the problem.  Until next time. 
> 
> When it's not working xrandr says HDMI-1 is disconnected, even though it 
> is connected.   Is there something I can do to  restore the second 
> display without the rigamarole of uninstalling/installing drivers?  I 
> tried using the second monitor's VGA input.  That works, but I then have 
> to use the sound card in the computer.  Because of the cable box, there's 
> an annoying hum in the audio.  I can deal with that by connecting a wire 
> from the case of the computer to an alligator clip which I connect to the 
> coax input to the cable box.  Then the clip comes off or I bump something 
> and that annoying hum is back. 
> 
> 
> Any ideas?  Thanks 
> 
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.phxlinux.org/mailman/listinfo/plug-discuss
---------------------------------------------------
PLUG-discuss mailing list - PLUG-discuss@lists.phxlinux.org
To subscribe, unsubscribe, or to change your mail settings:
http://lists.phxlinux.org/mailman/listinfo/plug-discuss