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Thread: Dual external monitors for Radeon HD 5450

  1. #1
    Join Date
    Jun 2010
    Posts
    2

    Default Dual external monitors for Radeon HD 5450

    Hey guys -

    I've been trying to get dual external monitors working on a Dell Studio 1458 / Ubuntu 10.04 laptop with an ATI Radeon HD 5450 to no avail. The laptop has two video outputs: HDMI and VGA. Some of my notes:
    * I've tried this using both Catalyst 10.4 and 10.5
    * I'd like to run this in multi-display desktop mode
    * One monitor is direct HDMI to DVI, the other is VGA to DVI
    * I can get a laptop + HDMI or laptop + VGA configuration working, but not an HDMI + VGA configuration
    * If I try to enable HDMI + VGA and disable the laptop monitor, only the HDMI connection displays anything

    Is it possible to run in an HDMI + VGA configuration (with the laptop monitor disabled)? Does anyone have any tips on other things to try? If it's not possible with the hardware, are there any other recommendations?

    Thanks for any help!

  2. #2
    Join Date
    Nov 2008
    Posts
    764

    Default

    fglrx doesn't support 3 monitors at a time yet, so you'll have to deactivate your internal panel.

    Two displays at a time should work. The correct way to do so is:

    1) enable one external display
    2) disable the internal panel, make sure it's off
    3) enable the second external display


    I can switch fine between monitor1 + monitor2 and monitor1 + projector using xrandr, I don't see why it wouldn't work on notebooks. Which tool do you use for switching?

    Of course the real test is usually: does it work on windows? If it does, it's a linux driver issue.

  3. #3
    Join Date
    Jun 2010
    Posts
    2

    Default

    I had been using the ATI Catalyst Control Center UI. I actually hadn't heard of xrandr until yesterday. Sure enough, setting up the dual-monitor configuration through xrandr worked flawlessly!

    Is xrandr the recommended way of configuring the displays instead of the Catalyst UI or aticonfig? It seems that the Catalyst UI works by changing xorg.conf and requiring restarts, whereas xrandr doesn't. Also, the "Monitors" preference app in Ubuntu never seemed to worked very well for me.

    Thanks for your help!

  4. #4
    Join Date
    Nov 2008
    Posts
    764

    Default

    yes, xrandr is recommended for the reasons you mentioned. Supposedly, CCC can handle some more exotic cases, but if xrandr works, stick to it.

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