I am having issues getting my second display to work properly in my latest install (Kubuntu 19.04). When I originally installed it, it would ask me (on startup) how to handle secondary display (See below) But my secondary display showed properly.
Now, for some reason, as you can see, image 1 is my hdmi output (works fine), and image 2 is the DVI monitor. The pictures actually make it seem better than it is. It's basically unusable. Fonts and small things (like icons and cursors) are the worst.
It almost looks like it can't anti-alias?
I've tried switching displays, it's not the monitor itself. swapping the cord causes the other monitor to do it. I've tried different cords also, same result. I would imagine it has to be my video card somehow, but I've not made any changes to it, or my configuration since I first built the machine (like a year ago). Have been using Windows mainly for the last little while, and decided to give Linux another go as my primary, and just VM to Windows when I need it.
When installing Kubuntu via my live usb, the display was fine. Seems to only affect the installed os.
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384 DisplayPort-0 disconnected (normal left inverted right x axis y axis) HDMI-A-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm 1920x1080 60.00 + 74.97* 50.00 59.94 1680x1050 59.88 1600x900 60.00 1280x1024 75.02 60.02 1440x900 59.90 1280x960 60.00 1366x768 59.79 1280x800 60.00 1280x720 60.00 50.00 59.94 1024x768 75.03 70.07 60.00 800x600 72.19 75.00 60.32 56.25 720x576 50.00 720x480 60.00 59.94 640x480 75.00 72.81 60.00 59.94 720x400 70.08 DVI-D-0 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm 1920x1080 60.00 + 74.97* 50.00 59.94 1680x1050 59.88 1600x1000 60.01 1440x1080 59.99 1400x1050 59.95 1280x1024 75.02 60.02 1440x900 60.00 1280x960 60.00 1280x800 60.00 1152x864 75.00 1280x720 60.00 50.00 59.94 1024x768 75.03 70.07 60.00 832x624 74.55 800x600 72.19 75.00 60.32 56.25 720x576 50.00 720x480 60.00 59.94 640x480 75.00 72.81 66.67 60.00 59.94 720x400 70.08
If I switch the display to the next highest resolution (1680x1050), it also looks fine, but I would much prefer to have both monitors on the same resolution.
There has to be some system configuration, because it's fine in Windows, and it's fine in the Linux Live environment.
Video card, if it ends up relevant is
Radeon RX 550 640SP / RX 560/560X according to
lspci | grep HDMI