I wonder if this is a known issue and if someone has any idea in which component the issue is.
I’m using Fedora/Gnome and Nvidia linux driver 430.34 (GTX 1070 card). The issue has existed in several past versions of the linux driver (as long as I’ve had this monitor). Monitor is Samsung LC34F791WQUXEN. This is an ultra-wide (21:9) 34" 100 Hz screen with freesync support. I use displayport cable directly connected to the screen.
After starting the PC and immediately starting a game with G-sync on (and with “Allow G-SYNC on monitor not validated etc.”), everything works fine. The game plays with G-sync and refresh rate looks variable (everything plays smooth and nice). On-screen indicators show FLIP - VSYNC ON and G-SYNC. But when I pause the game and let the Gnome screensaver lock the screen, then unlocks screen and continue gaming, the monitor starts to turning the input off and on every few seconds (like it has lost the signal). To get it to stop losing signal you must quit the game or alt-tab to desktop. This stops the input signal flipping. Now to get it to work again in the game, you can reboot the PC, or simply turn off g-sync in Nvidia settings. Another way without rebooting is to change Resolution in Nvidia-settings from Auto to 3440x1440 and then set resfresh rate to 60 Hz (sometimes toggling a couple of times between 60 and 100 Hz is necessary). Then when starting the game it is like the driver “takes over” and G-sync then drives the refresh rate up to 100 Hz and keeps it on. So toggling screen refresh rate somehow resets the issue.
To me this looks like something maybe in gnome-shell or mutter “disturbs” the Nvidia driver g-sync feature and “takes over” refresh of the screen. There is nothing in logs that would tell anything about the problem. I haven’t found anything similar reported in gnome and mutter issues at their gitlab.
Also when the screen is in the “signal loss mode” (with g-sync turned on) and start for instance VLC media player, the screen also starts losing signal in the same way when viewing video in fullscreen mode. Solution is to turn off g-sync or reboot the computer (or doing the same refresh rate toggling).
As I don’t know in which component this problem lies, I’m asking here now.