Multi-Monitor on LiveCD = perfect; installed = not-so-much

[Mehtuus]

I first tested my system via the LiveCD. Everything worked perfectly with only minor adjustments. Unfortunately, after installing I was in for a huge let down.

My System:
Kubuntu 16.04 (x64)

Plasma v5.5.5
Qt v5.5.1
Kernel v4.4.0-28

MB: Asus Z97-E

Onboard Intel VGA output switched ON

CPU: i7-4790K
RAM: 5.70 GiB
Nvidia GeForce GTX 460

driver v361.42

I have three monitors connected to the system. Two on the GTX 460, and one on the onboard VGA port. This setup works in Windows 10 and the Kubuntu 16.04 LiveCD. However after installing Kubuntu, both monitors attached to the GTX work fine, but the third monitor (attached to the onboard VGA port) does not function. It doesn't even show up in "Display Configuration" like it did on the LiveCD.

I don't understand why it worked fine on the LiveCD but was a total fubar after installing. Any ideas on how a frustrated Kubuntu user can get it working like it did in the LiveCD?

[Rod J]

My guess is the Nvidia proprietary driver that you've installed (which the live CD didn't use) isn't playing nicely with the generic driver for the onboard graphics. Alas, I've no idea how to fix that as I haven't had a discrete graphic card for years and run all three of my monitors from the onboard graphics (Intel Core-i5 Haswell).

[Mehtuus]

Now that you mention it, I don't strictly remember the setup routine asking for permission to install Nvidia drivers, but with all that I have going on atm it may have and I spaced it. I'll have to check into it some more.

[dequire]

Worth a read and also a call to action from KDE's Martin Gräßlin: Multi-screen woes in Plasma 5.7. Bottom line - report bugs so this can be fixed properly and once and for all.