I have just installed Ubuntu 12.04.1 LTS in my computer with 2 monitors, but when I open "Displays", just one is shown.
Im running a NVIDIA card.
If you need anymore information, tell me and Ill add it.
What am I missing?
Essentially this fix should solve the Dual screen not recognized problem. It did for me.
Symptoms I was encountering were:
sudo /usr/lib/nux/unity_support_test -p
Error: no composite extension.
Additionally when I attempted to open the Displays setting dialog, it would error saying something about RANDR and then never open even crashing Ubuntu a few times presenting the reporting dialog.
Some back story: I have an nVidia GeForce 8800GTS. When I booted the LiveCD of 12.04LTS 32bit, it booted with a fancy high-resolution grub, high resolution text mode, and right into unity with full 3D. After a while, ubuntu told me about proprietary drivers I should install, so I did. I installed the [recommended] one but upon rebooting, unity was stuck in 2D mode. So began my search for the fix.
I had been fighting with this issue for the past few days and successfully got unity running in 3D again by doing the following steps:
sudo add-apt-repository ppa:ubuntu-x-swat/x-updates sudo apt-get update sudo apt-get dist-upgrade
sudo nano /etc/default/grub (and uncomment the GRUB_GFXMODE) GRUB_GFXMODE=1680x1050 sudo nano /boot/grub/grub.cfg linux /boot/vmlinuz-3.2.0-32-generic-pae root=UUID=a9aa4a63-ac9c-4fc4-96d8-7861d155d376 ro quiet splash $vt_handoff nomodeset sudo update-grub
sudo service stop lightdm sudo nvidia-xconfig --composite sudo service start lightdm
So, in all I think it was step 1, and 3 that fixed this for me. Step 2 just made the boot graphics high-res and gave me the super fine text mode I had on my install.
edit
To solve the dual displays issue, I was encountering and giving me access to the Displays settings, I had to stop using xinerama and switch to using Twinview in the nvidia-settings program.
I erroneously thought this would clone/mirror the displays and was using xinerama instead thinking that was the only way I could get both displays to work, but TwinView does exactly what I want; and because I'm no longer using xinerama, Ubuntu Display settings dialog does open (before it was showing RANDR error) and shows two displays.
You will need to install the NVidia drivers, if you have not already. You should be able to find these under System Settings -> Additional Drivers -> NVIDIA accelerated graphics driver (version current)
.
Unfortunately, the NVidia binary drivers do not fully stick to standards for describing multiple monitors. The System Settings -> Display
window will show only a single large "screen" spanning both monitors. To configure your dual monitors, you need to use the NVidia X Server Settings
tool which should have been installed along with the drivers.