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I am using a Toshiba laptop with an ati radeon graphics card. I have installed ubuntu 12.04 via wubi. I am trying to output to my external display which has a native resolution of 1280x768, but it is being recognised as an unknown display and limited to 1024x768. I have installed all updates and the additional drivers section in the system settings says there are no proprietary drivers available.

When I use the much discussed cvt and xrandr method I get this:

~$ xrandr
Screen 0: minimum 320 x 200, current 1280 x 800, maximum 8192 x 8192
VGA-0 connected (normal left inverted right x axis y axis)
   1024x768       60.0  
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
HDMI-0 disconnected (normal left inverted right x axis y axis)
LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 331mm x 207mm
   1280x800       60.0*+
   1280x720       59.9  
   1152x768       59.8  
   1024x768       59.9  
   800x600        59.9  
   848x480        59.7  
   720x480        59.7  
   640x480        59.4  
DIN disconnected (normal left inverted right x axis y axis)

~$ cvt 1280 768
# 1280x768 59.87 Hz (CVT) hsync: 47.78 kHz; pclk: 79.50 MHz
Modeline "1280x768_60.00"   79.50  1280 1344 1472 1664  768 771 781 798 -hsync +vsync

~$ xrandr --newmode "1280x768_60.00"   79.50  1280 1344 1472 1664  768 771 781 798 -hsync +vsync

~$ xrandr
Screen 0: minimum 320 x 200, current 2304 x 800, maximum 8192 x 8192
VGA-0 connected 1024x768+1280+32 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0* 
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
HDMI-0 disconnected (normal left inverted right x axis y axis)
LVDS connected primary 1280x800+0+0 (normal left inverted right x axis y axis) 331mm x 207mm
   1280x800       60.0*+
   1280x720       59.9  
   1152x768       59.8  
   1024x768       59.9  
   800x600        59.9  
   848x480        59.7  
   720x480        59.7  
   640x480        59.4  
DIN disconnected (normal left inverted right x axis y axis)
  1280x768_60.00 (0x2da)   79.5MHz
        h: width  1280 start 1344 end 1472 total 1664 skew    0 clock   47.8KHz
        v: height  768 start  771 end  781 total  798           clock   59.9Hz

~$ xrandr --addmode vga-0 1280x768_60.00
xrandr: cannot find output "vga-0"

Even though xrandr tells me that vga-0 is connected, if I try any commands with vga-0 it tells me that it cannot find output vga-0

I am a complete n00b so please bear with me.

Any advice would be much appreciated.

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1 Answer 1

up vote 1 down vote accepted

I believe the displays used in xrandr are case-sensitive. I noticed you said vga-0 instead of VGA-0 so double check!

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thank you so much! I had been struggling with that the last couple days! Can't believe it was something so silly! –  user260018 Mar 19 at 21:33
    
Could you be so kind as to post some step by step instructions on how to make these changes persistent? I have looked around but I am struggling to understand the process. I am a real n00b. sorry. and thanks in advance. –  user260018 Mar 19 at 23:10
    
That needs to be configured in the xorg.conf. It used to be in /etc/X11/xorg.conf but I think they changed it to a newer system in the newer versions of ubuntu. The xorg.conf files lets you put in such parameters like display resolution or things like multiseating that reads on boot. –  Mr.Lee Mar 19 at 23:18

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