After some struggle to install one quadro fx 580 and one geforce 210 graphic cards on ubuntu mate 20.04 using nvidia 340.108 driver i noticed that the xrandr does not recognize 2 X screens. The only way I could make it to work was by xinerama but I want 4 individual displays not one big stretched screen.
Is ubuntu mate descktop supporting something like this?
Have you tried xrandr --screen [screen number] [other options to xrandr] yet? That should work on any X screen: 0, 1, 2 or 3.
I used xconf for setup. Only the main gpu's displays are recognized by xrandr, both on the same x screen.
Edit.
After some digging I found this:
xrandr --setprovideroutputsource 1 0
https://bbs.archlinux.org/viewtopic.php?id=189506
I'll test this asap. Thank you.
$ xrandr --listproviders
shows only primary gpu...
Provider 0: id: 0x249 cap: 0x1, Source Output crtcs: 2 outputs: 4 associated providers: 0 name:NVIDIA-0
$ xrandr
Screen 0: minimum 8 x 8, current 3280 x 1200, maximum 8192 x 8192
DVI-I-0 connected primary 1680x1050+1600+0 (normal left inverted right x axis y axis) 473mm x 296mm
1680x1050 59.95*+
1440x900 59.89
1280x1024 75.02 60.02
1280x960 60.00
1152x720 60.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
VGA-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 367mm x 275mm
1600x1200 60.00*+
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
DVI-I-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
I created the same question here to get more attention. https://askubuntu.com/questions/1335280/xrandr-cant-see-more-than-one-x-screen-with-dual-gpu-video-cards-and-4-monitors