[SOLVED] Strange "Input not supported" error

[Gorgatrounce]

Hi there. I have a very specific error that has been cropping up since the installation of my new GPU.

Under certain circumstances, when the computer is waking up from Sleep Mode, I will get an "Input Not Supported" message on an otherwise black monitor. If I hard cycle the power, it boots up mostly normally...it will say "Input Not Supported" until Windows initialises (and the drivers load, I presume) and then run fine.

The circumstances are quite specific. It wakes from Sleep normally, unless I have been running (just about any) video game using full screen. If I've done that, I get the error message the next time it sleeps.
Moreover, I have reassigned the power button to Sleep (rather than on/off). If I wake the computer and get "Input not Supported", I can press the power button (putting it back to sleep) then press the power button again (to wake it up) and the video comes back without having to power cycle.

I have disabled rapid start up in the BIOS. I have tried rolling back and reinstalling drivers for the GPU.
Running Windows 7 Home Premium
GPU is Radeon RX 5700 XT which unfortunately does not have DVI out, or I'd try that...it has some 1.4 outputs, but I do not have a 1.4 cable...should I try buying a 1.4 to HDMI cable? They are quite pricy!
Current driver I am running with is 27.20.20903.8001
I have tried a couple of monitors with the same results (or just black screen in some cases)

Grateful for any suggestions!

 

[Colif]

what monitor is it? the message will be from the screen itself.
Is it an Acer screen? its something to do with the resolution
https://www.minitool.com/news/input-not-supported.html

 

[Gorgatrounce]

Colif, it's an Acer G276HL monitor. I didn't think it was a monitor issue, because I had tried it with...other Acer monitors.
Thanks for the link! My reading of the issue on that article is that "Acer monitors aren't always great, and you basically just have to live with this issue."