How can I set up dual monitor display with ATI driver?

I have 11.10 running on a system76 laptop. without the proprietary driver i was able to set up a second monitor (samsung 19") with extended display.

when i activate the proprietary driver, the only display setting that works is "mirror". when i pick to extend the display at the proper resolution (1280:1084, samsung) (1600:900, laptop) for each screen I get the following:

required virtual size does not fit available size: requested=(2880, 1024), minimum=(320, 200), maximum=(1600, 1600).

when i try to execute the resolutions that are set at default, after unchecking the "mirror screens" button (1152:864, samsung) (1600:900, laptop) i get the following:

requested position/size for CRTC 148 is outside the allowed limit: position=(1152, 0), size=(1152, 864), maximum=(1600, 1600)


Type in this command, to open the AMD Catalyst Control Center

gksudo amdcccle
  1. Go to Display manager > There you must see your monitors.
  2. Click on the Monitor you want to setup display on
  3. Go to Multiple Screen Tab
  4. Change the display mode to your choice
  5. Apply this and restart

Open a terminal and type:

gksudo gedit /etc/X11/xorg.conf

In the sub-section "display" add this code or modify if already exist:

virtual 2880 1024

Where 2880 and 1024 are the value returned by the error: required virtual size does not fit available size: requested=(2880, 1024), minimum=(320, 200), maximum=(1600, 1600).

Restart the computer.

Then you will be able to extend your desktop without issue.