Dual head is OK, triple head fails with a new monitor (details within)


GPU: MSI GFX970 (support up to 4 screens)
Driver version: 346.22

System: Ubuntu 14.04 x64

Driver is installed via the xorg-edgers PPA

Old setup:

Left: Viewsonic 19" screen, 1280x1024 @ 75Hz, using DVI connection
Right: Samsung 24" HD screen, 1980x1080 @ 60Hz, using HDMI connection

Dualhead works perfectly fine with this setup.

New monitor is a iiyama 24" HD screen (capable of up to 144Hz). It is connected using DisplayPort.

Plug this in with PC powered down.

Start up into Ubuntu.

The two old screens are fine.

I go into NVidia X Server Settings app to setup the new screen and config it with this layout:

Left: Viewsonic 19" screen, 1280x1024 @ 75Hz, using DVI connection
Centre: iiyama 24" HD screen, 1980x1080, using DisplayPort
Right: Samsung 24" HD screen, 1980x1080 @ 60Hz, using HDMI connection

It goes all blank and I am unable to do anything, even pressing Ctrl-Alt-F1 to drop to terminal does not work. So had to hard powerdown and restart in safe mode and go into root to remove the newest xorg.conf file from /etc/X11 and replace with the previous backup.

This is what I did to get triple head working:

Disconnect the old Viewsonic monitor.

Go into Nvidia Settings and enable the iiyama monitor and disable the Samsung monitor and apply. It works on its own.

Enable the Samsung monitor to the right and apply.

Dual head works - but I get an error message “The selected configuration for displays could not be applied. could not set the configuration for CRTC 443” and a Close button.

If I ignore this error message, dual head works just fine.

Sometime if I close this error message, the new screen stop working but this isn’t always reproducible.

I then reconnect the old Viewsonic monitor while still powered on. Nvidia Settings shows this new screen.

I then add this as a 3rd screen to the left of iiyama screen. This works.

I now have triplehead, but I get an error message which if closed can kill the new screen and I have to reset everything again.

Rebooting requires me to reconfigure it all again.

I don’t reboot very often as am working on projects but this is also my gaming machine with some games that are Windows only so that’s when I reboot for those games not on Linux.

Please see the logs collected via the nvidia-bug-report.sh tool hosted on Dropbox:


If there is anything else that is required, please do let me know and I’ll do my best to help.