Here's another good test: reverse the monitors.

Does the flicker follow the monitor or stay in the same position?

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From: Evan Leibovitch via talk
Sent: Sat Apr 03 16:54:31 EDT 2021
To: "D. Hugh Redelmeier"
Cc: Evan Leibovitch , Evan Leibovitch via talk
Subject: Re: [GTALUG] flickering [was Has the graphics-card world gone mad?]

Sorry, just saw this buried under a whole bunch of crap. Thanks for the offer of help.

Here is the config.
Once ran Linux and was driving me crazy, now runs Windows.

The monitors: Two identical 28" Samsung 4K monitors (model U28E590D), mounted vertically.
The video card has one DVI, one Displayport (connected to the right screen) and one HDMI (connected to the left screen).


When the system boots up (ie, the motherboard logo and "press DEL for setup") that shows up on the right screen only.
OS Login right screen only.
Once logged in the second screen comes alive, configured side by side such that the wallpaper is scaled to fit both screens so it looks like one screen (except for the bezel)..
I can scale a window across both screens.
So far, all driver settings are on default. The Windows app for the Radeon has many settings I don't understand.

What *exactly* do you mean by flickering?

The right (displayport) monitor is solid and reliable.

The left (HDMI) screen will (randomly to me) do one of a few things:
  1. Go off (the monitor reports lost signal) and back on after about 1-2 seconds.

  2. Go off (no signal) for 3-4 seconds and then back on, briefly to flat green or static and then normal.
Frequency appears random, averaging about 5-10 per hour, slightly more frequent if I am watching video (either youtube on a browser or VLC locally). Scenario 1 above (just blank) happens far more frequently than #2, but #2 happens enough to be noticeable.In the time it's taken me to write this I've had three of #1 and one of #2

I've tried different cables, no difference.
 
What loads cause flickering to happen?

It will happen when I'm not doing anything.  I've just now run a not-too-taxing game using Steam (pinball) on each screen, no difference.

If you force the monitors to a reduced resolution does the flicker go away?

TBH, haven't tried that.

Is any of this helpful?

- Evan

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