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I've done an Ubuntu 16.04 fresh installation and now my dual monitors don't work after booting.

This is what happens during booting:

  1. When I boot, the main monitor works and asks for my HD password (I've chosen to encrypt the HD during Ubuntu 16.04 install). The second monitor is out of signal.

  2. Ubuntu asks for my user password. Sometimes it appears on the first monitor, sometimes on the second monitor. However, only the first is active (so when it appears on the second monitor I have to guess it is there). Nonetheless, it still works like it is being displayed.

  3. When using Ubuntu, only the first display will be active. I have to open the display setting, deactivate the second monitor (yes, Ubuntu thinks it is activated, even though it is not working), and the reactivate the second monitor.

    I have to do this every time I boot. Sometimes the monitor settings window appears at the second monitor (thus, I cannot change the settings).

Now I've detached the second monitor and every time after boot I plug it in and then change the display settings.

Any ideas of what the problem might be?

Community
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user60011
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  • When I run "lspci | grep VGA" on the terminal it returns:00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Trinity [Radeon HD 7560D] – user60011 Apr 26 '16 at 15:53
  • Same problem for me second screen doesn't work anymore.... – psv Apr 29 '16 at 08:59
  • Same problem since I have upgraded Ubuntu Gnome to version 16.04. I have a VGA and a DVI connectors. If during booting the DVI monitor is plugged, everything is fine. If the DVI is unplugged, the VGA doesn't work, at least until i try plugging and unplugging monitors when the computer is already on. If I plug the DVI, also the VGA starts working! – Federico Picetti Sep 07 '16 at 16:54
  • The video card may output a refresh rate the monitor does not like. – Thorbjørn Ravn Andersen Feb 05 '20 at 12:51

1 Answers1

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I have exactly the same problem. I have two monitors, one on DVI, one on VGA. Everything worked fine with Kubuntu 15.10.

Now, with 16.04, you can see that during the boot up, the VGA monitor stays black, but Ubuntu thinks it activated it. Also for me, the only workaround is to deactivate the second screen in the system settings and to re-activate it. Then, in 99% of the cases it works.

I have a AMD/ATI onboard graphic card, and it seems this is the source of our problem, see here: http://www.omgubuntu.co.uk/2016/03/ubuntu-drops-amd-catalyst-fglrx-driver-16-04

(German)http://www.golem.de/news/xenial-xerus-ubuntu-16-04-verzichtet-auf-proprietaeren-amd-treiber-1603-119679.html

So we can only hope that the open source drivers will improve soon..... :-/

Mondlicht
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