Tuesday, November 24, 2009

Dual Monitors

I retired an old computer and tried attaching its monitor to my new computer. I have an nvidia video card which can handle this with UltraMon on Windows XP. So, I already know that it is, in principle, possible.

Since I have been playing around with linux for several years now, I have gotten used to editing manually the xorg.conf files. Today, I found a line saying:"some configuration settings that could be done previously in this file, now are automatically configured by the server and setings here are ignored". So, I had to use the nvidia application.

Before following the systematic steps listed below, I encountered these problems:
  1. Both monitors did not show images, but instead displayed a message "Not optimal resolution" in a square window, drifting about on the monitor.
  2. My monitors were reversed but not the resolution. So, the small monitor had the resolution of the larger, and the larger had a small square taking up half its space.
Method I used to get it working:
  1. At the command line (in an xterm window), type:

    sudo /usr/bin/nvidia-settings

    The pull down menu for nvidia (system->Administration->NVIDIA X Server Settings) does not ask for a password, which is what you need to save the settings. There is a way to change this in the menu but I forgot (TBD). The best is to just find the command (do a ps -ef at the command line when nvidia application is open and you can see what it is called and where it is)
  2. Make sure your primary monitor (the one right in front of you) is correctly installed. I confess, I re-installed Ubuntu. Then ran the nvidia settings command.
  3. I see a greenish window with some system information. (X Server information on the left panel).
  4. Click on X server display configuration and I see my primary monitor, name and resolution.
  5. I plugged in the second monitor, I clicked on "Detect Displays" and the second monitor was found and displayed as a square with the word disabled on it. Clicking configure finds the resolution.
  6. When asked to save, there is a little box that asks if you want to merge with the old xorg.conf. I printed out the old and the new, and decided to unclick the merge. Otherwise, there would have been three monitors in the xorg.conf and that might have been one of the reasons I was having trouble.
  7. Reboot (constantly) and I got two monitors, each with a desktop and its own taskbar. But...opening a window on the second one resulted in an error window which I could not read but would not go away.
  8. Return to the nvidia settings application, I tried the Xinerama button.
  9. Reboot and I have what I want, although not as good as Ultramon can do for me on Windows XP. There is no separate taskbar, for example, and no handy button to move the application. I have to drag it there.
  10. Since all I really wanted was a place to display user manuals while learning an application on my primary monitor, this is just fine and I am going to leave it.
This took me several hours.

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