I am using Ubuntu 14.04. I have an AMD Radeon 5570 HD graphic card. Actually, the default open source REDWOOD drivers aren't allowing me to choose my monitor's maximum screen resolution(which is 1366 x 768). I just have two resolutions displayed which are 1024x768 and 800x600 . If I give the command :

xrandr -s 1366x768

then the output is:

Size 1366x768 not found in available modes

So just for the sake of getting 1366x768 resolution I am forced to install the proprietary graphic driver that AMD gives me from its site. But if I install it(which itself is quite a problem-prone process), I undergo a lot of 'inconvenience'. Sometimes after an OS update, the driver crashes unity. Then I will have to uninstall that driver from a tty and google around for a solution. Also I encounter screen tearing problems occasionally. In addition I also cant see my login screen(See this question which states this particular problem). The main problem is AMD does not update its driver as quick as Ubuntu updates its OS. This is quite irritating.

So, I want the maximum resolution(and performance) that my graphics card and monitor can give me without installing the 'problematic' proprietary graphic card driver that AMD gives. Is this possible? Suggestions please. Thanks in advance.

PS :- More system specs details:-

  • Intel i3 2100 processor
  • AMD P8H61-M PLUS2 motherboard
  • AMD Radeon 5570 HD graphic card
  • DELL monitor

(BTW, Thank you for reading through my elaborate description!)


2 Answers 2


I didn't see any errors in the Xorg.0.log file the radeon driver seems to work well so try to create a Modeline for the unsupported resolution. Open a terminal with Ctrl+Alt+t and type:

cvt 1366 768

It should return:

# 1368x768 59.88 Hz (CVT) hsync: 47.79 kHz; pclk: 85.25 MHz
Modeline "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync

Now try to create a new mode for xrandr using this Modeline:

xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync

Finally apply the new mode to your desired output:

xrandr --addmode DVI-0 1368x768_60.00

Note: Change DVI-0 by your current active output, check the result of the xrandr command to know which one to choose.

EDIT: How to force lightdm to use this specific resolution:

  1. Create a shell script in /usr/bin called lightdmxrandr.sh containing:

    xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync
    xrandr --addmode DVI-0 1368x768_60.00
    xrandr --output DisplayPort-0 --off --output DVI-0 --mode 1368x768_60.00 --pos 0x0 --rotate normal --output HDMI-0 --off
  2. Make /usr/bin/lightdmxrandr.sh executable:

    sudo chmod +x /usr/bin/lightdmxrandr.sh
  3. Modify your lightdm settings:

    sudo gedit /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

    to add the following line:


    This will set the login screen resolution. To set the desktop resolution, do the following:-

  4. Open Startup Applications. One can do so from the dash.

  5. In the startup applications window select "Add". Then give a name of your choice. Then press browse and select lightdmxrandr.sh from /usr/bin. Now select "Add". Make sure there is a tick mark before the entry you just added and then close the window.

Now reboot. Both your login screen and desktop must have the 1366x768 resolution.

PS:- Credits for the last part of the answer go to this question here.


OS: Ubuntu 16.04. Graphics card: AMD Radeon HD 7850. Gallium 0.4 open source driver.

Dual monitors connected: HDMI-0; DVI-0.

HDMI resolution: 1600x900. DVI should display 1366x768, but defaults to 1024x768. DVI's monitor resolution was not detected. Adding undetected resolutions

HDMI EDID matrix data parses. DVI EDID matrix data does not parse using xrandr --verbose.

Wrote script which specifies xrandr newmode/addmode/output for DVI display.

xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync
xrandr --addmode DVI-0 1368x768_60.00
xrandr --output DisplayPort-1 --off --output DisplayPort-0 --off --output DVI-0 --mode 1368x768_60.00 --pos 1600x132 --rotate normal --output HDMI-0 --primary --mode 1600x900 --pos 0x0 --rotate normal

Added that shell script to startup programs listed in gnome-session-properties.

DisplayPort-0 and DisplayPort-1 are unused ports which have been disabled in BIOS.

reference: Ubuntu Wiki: Resolution

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