14.04 LTS unknown display, 1024x768 only

Question

I am having problems with my ubuntu-installation. Here is the whole story:

Step 1

I installed Xubuntu 15.10 on my old PC (Intel D510MO where I just upgraded 4GB of DDR2)

Display only shows up with 1024x768 and couple of lower resolutions. I find this thread: Wrong Screen Resolution on an Intel D510MO

However, going to settings -> displays doesn't show the "laptop" and just says "Display" and I can't take of any mirrorings or anything. Finally I decide to try

Step 2

I install 12.04 LTS and this time I do find System Settings -> Displays with 2 monitors and I can do as instructed in the thread. However, the display that I have connected is "unknown display" and still only 1024x768 with the fix given in the thread.

Step 3

I upgrade to 14.04 LTS and display stays unknown and only 1024x768 available. Now the "laptop" display has dissappeared and I only have the unknown one. I keep searching help and find this thread: Ubuntu 14.04 Unknown Display

I can't find additional drivers from Software and Updates -> Additional Drivers, but I run sudo apt-get install intel-microcode and reboot. No help there. I find this and follow the link and edit my /etc/default/grub and run sudo update-grub + reboot. Again with no luck. I even found the thread where I was told to edit my ~/.config/monitors.xml and some other files and reboot, but even that didn't help. Gave some errors on reboot tho.

Now Im totally run out of ideas and google just gives the same pages over and over again. I have VGA-cable and my display supports FullHD resolution and that is what I wanna use. Can you please help me?

Here is my lspci -v

00:00.0 Host bridge: Intel Corporation Atom Processor D4xx/D5xx/N4xx/N5xx DMI Br
idge (rev 02)
    Subsystem: Intel Corporation DeskTop Board D510MO
    Flags: bus master, fast devsel, latency 0
    Capabilities: <access denied>
    Kernel driver in use: agpgart-intel

00:02.0 VGA compatible controller: Intel Corporation Atom Processor D4xx/D5xx/N4
xx/N5xx Integrated Graphics Controller (rev 02) (prog-if 00 [VGA controller])
    Subsystem: Intel Corporation DeskTop Board D510MO
    Flags: bus master, fast devsel, latency 0, IRQ 45
    Memory at e0300000 (32-bit, non-prefetchable) [size=512K]
    I/O ports at 30c0 [size=8]
    Memory at d0000000 (32-bit, prefetchable) [size=256M]
    Memory at e0200000 (32-bit, non-prefetchable) [size=1M]
    Expansion ROM at <unassigned> [disabled]
    Capabilities: <access denied>
    Kernel driver in use: i915

Answer 1

You can use xrandr:

The commands to be executed in order:

cvt 1920 1080
xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync

The part of the line after xrandr --newmode is similar to the ouput you should get when using the cvt command, so copy the output from the "resolution_refreshRate" to the +vsync point and add it to xrandr --newmode.

Then:

xrandr --addmode LVDS1 resolution_refreshRate (don't use speechmarks)
xrandr --output LVDS1 --mode resolution_refreshRate

If you want to make the changes permanent:

• Create a bash script, xrandr.sh for example, and place your xrandr commands into it:

  #!/bin/bash
  sudo xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
  sudo xrandr --addmode Virtual1 1920x1080_60.00
  xrandr --output Virtual1 --mode 1920x1080_60.00

• Make the script executable with chmod +x xrandr.sh

• Search for "Startup Applications" in the dash, run it, and add the script as a startup application.

The commands will now run every time you log into your account.

Note: I'm using LVDS1 as the supposed monitor name, but yours probably won't be the same. You can find your monitor name using:

xrandr | grep " connected " | awk '{ print$1 }'

This might be useful to you.

Answer 2

I had the same problem with my Samsung monitor, after a lot of reasearch i found that I was using VGA cable and monitor was not detected, connecting through HDMI solved the problem and all resolutions are now listed. However, VGA all works fine with Windows.

Answer 3

I found a solution to this problem. Firstly, let me explain my problem if it fits with your problem.

My display is LG Flatron W2243S. It supports 1920x1080. But although I connect it to my PC via VGA, it is detected as unknown display and I can't use more than 1024x768 efficiently. I mean there is 1280x720 as maximum resolution in the settings of that 'unknown display' and if I choose it, I lost the left quarter of the screen, namely the mouse arrow disappears in that left quarter region.

After some research I found a solution that works for me. I replaced the VGA cable and screen is detected as '22" Display' not 'LG ...sth.'. However, I can choose 1920x1080 finally and it works perfectly.

To sum up, problem is caused by VGA cable and I replaced it with another one.