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Hello everybody. Up until now I've had just 2 monitors, and a single (ati) video card driving both. Everything was fine. I wanted a third monitor, so I bought another ...
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  1. #1
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    How to correctly configure xorg.conf for triple monitors?


    Hello everybody. Up until now I've had just 2 monitors, and a single (ati) video card driving both. Everything was fine. I wanted a third monitor, so I bought another video card, (nvidia) plugged it in, long story, made a xorg.conf, and my third monitor is working. However I have 2 slight problems.

    The left most monitor, (the one and only monitor the nvidia card is driving) has "it's own desktop." What I mean by that is this. It does not have any of the icons my other 2 monitors have, and it has it's own gnome bar (is that the right word? Like it's the bar on the top that has Applications, Places, System) at the top. Also, I am unable to drag applications windows from the other 2 monitors onto it.

    The next problem is, the other 2 monitors (being driving by the Radeon card) are working as they should, except now whenever I maximize something, it maximizes across both monitors, instead of maximizing within just 1 monitor. I do not care for this configuration.

    Do you know if it's possible for me to reconcile either of these issues? Here's my current xorg.conf

    Code:
    Section "Device"
        Identifier "ati-card"
        Driver     "radeon"
        BusID      "PCI:01:00:0"
    EndSection
    
    Section "Device"
        Identifier "nvidia-card"
        Driver     "nv"
        BusID      "PCI:04:02:0"
    EndSection
    
    Section "Monitor"
        Identifier "left-montior"
    EndSection
    
    Section "Monitor"
        Identifier "middle-monitor"
    EndSection
    
    Section "Monitor"
        Identifier "right-monitor"
    EndSection
    
    Section "Screen"
        Identifier "left-screen"
        Device     "nvidia-card"
        Monitor    "left-monitor"
    EndSection
         
    Section "Screen"
        Identifier "middle-screen"
        Device     "ati-card"
        Monitor    "middle-monitor"
    EndSection
    
    Section "Screen"
        Identifier "right-screen"
        Device     "ati-card"
        Monitor    "right-monitor"
    EndSection
    
    Section "ServerLayout"
        Identifier     "Default Layout"
        Screen      0  "middle-screen" 0 0
        Screen         "left-screen" LeftOf "middle-screen"
        Screen         "right-screen" RightOf "middle-screen"
    EndSection

  2. #2
    Linux Guru Rubberman's Avatar
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    Part of the problem is (I think) the fact that you have 2 different card manufacturers, AMD and nVidia. So, there are at least 2 different video configuration tools that are working at counter-purposes. If you can swap out the AMD/ATI card for another nVidia one, then you should be able to drive all three in a "twinview" virtual desktop environment. Unfortunately, I am not enough of an expert on the Xorg.conf settings needed to make this work with a mix of AMD + nVidia devices.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

  3. #3
    Linux Newbie SL6-A1000's Avatar
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    I am pretty confident that what u've got is the best ur going to do.
    The problem isn't software, as u could configure it how u want with a triple display.
    However it still won't work because at a hardware level they r working independently meaning u always get the display running of the other GPU working seperately.
    This where u need the same model card in SLI or crossfire. E.g 2 nvidia 560's.
    SLI will allow them to recognize each other to interact

  4. #4
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    I have the same exact problem. I have three screens, two on one card, and one on the other. I have two identical PNY GeForce GT620 graphics cards, so at least for me, going across two vendors is not the issue here. I am using nvidia-settings to do the configuration, and the best I can do to use all three screens is to have two in Nvidia TwinView, and one as a completely separate XSession.

    I'll let you know if I figure anything out. I do intend to play games across all three screens .

  5. #5
    Just Joined! krokoziabla's Avatar
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    Hey, and what about Windows? I have 3 monitors and 2 videocards as well (Intel HD Graphics integrated and Radion HD at PCIEx16), and two OSs on my PC - Windows and Ubuntu. When I installed Windows and video drivers for both cards then Windows without my involvement configured both cards in the way that I had one desktop spread over three displays. I'm a programmer and due to development environment I have to use Windows most of the time so I haven't had time to dig into it and try configure my Linux properly. But as well I would like to have one common GNOME desktop spread over three displays at my Linux.

    So if it is easily configured in Windows and it doesn't depend on HW why should it be impossible in Linux?

  6. #6
    Linux Guru Rubberman's Avatar
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    Quote Originally Posted by krokoziabla View Post
    Hey, and what about Windows? I have 3 monitors and 2 videocards as well (Intel HD Graphics integrated and Radion HD at PCIEx16), and two OSs on my PC - Windows and Ubuntu. When I installed Windows and video drivers for both cards then Windows without my involvement configured both cards in the way that I had one desktop spread over three displays. I'm a programmer and due to development environment I have to use Windows most of the time so I haven't had time to dig into it and try configure my Linux properly. But as well I would like to have one common GNOME desktop spread over three displays at my Linux.

    So if it is easily configured in Windows and it doesn't depend on HW why should it be impossible in Linux?
    I don't think it's impossible, just difficult. It's one of those unfortunate situations where Windoze "does it right", and Linux makes you learn how to pull rabbits out of a hat...
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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