I'm trying to set up a triple monitor desktop at my office using Fedora 17, but it seems impossible, let me explain the setting:

  • Laptop ASUS K53SD with 2 graphic cards, Intel and nVidia (Screen controled by Intel card)
  • 24" Full HD monitor connected to the HDMI output (controlled by Intel card)
  • 23" Full HD monitor connected to an USB-HDMI adapter (via framebuffer in /dev/fb2, apparently)
  • VGA output (not used) controlled by nVidia card

First of all, the USB-HDMI adapter works perfectly, it gives me a green screen (which means the communication is OK) and I can make it work if I set up a single monitor setting via framebuffer in Xorg. Here I leave the page where I got the instructions: http://plugable.com/2011/12/23/usb-graphics-and-linux

Now I'm trying to set up the the two main monitors (laptop and 24") with the intel driver and the 23" with the framebuffer, but the most succesful configuration I get is the two main monitors working and the third disconnected.

Do you have any idea what can I do to make this work?

Here I leave my xRandr output and my Xorg conf:

-> xrandr
Screen 0: minimum 320 x 200, current 3286 x 1080, maximum 8192 x 8192
LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768       60.0*+
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA2 disconnected (normal left inverted right x axis y axis)
HDMI1 connected 1920x1080+1366+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      60.0*+   50.0     25.0     30.0  
   1680x1050      59.9  
   1680x945       60.0  
   1400x1050      74.9     59.9  
   1600x900       60.0  
   1280x1024      75.0     60.0  
   1440x900       75.0     59.9  
   1280x960       60.0  
   1366x768       60.0  
   1360x768       60.0  
   1280x800       74.9     59.9  
   1152x864       75.0  
   1280x768       74.9     60.0  
   1280x720       50.0     60.0  
   1440x576       25.0  
   1024x768       75.1     70.1     60.0  
   1440x480       30.0  
   1024x576       60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   720x576        50.0  
   848x480        60.0  
   720x480        59.9  
   640x480        72.8     75.0     66.7     60.0     59.9  
   720x400        70.1  
DP1 disconnected (normal left inverted right x axis y axis)
   1920x1080_60.00   60.0  

The Xorg file:

# Xorg configuration file for using a tri-head display

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "HDMI" 0 0
    Screen      1  "USB" RightOf "HDMI"
    Option         "Xinerama" "on"

########### MONITORS ################

Section "Monitor"
    Identifier     "USB1"
    VendorName     "Unknown"
    ModelName      "Acer 24as"
    Option         "DPMS"

Section "Monitor"
    Identifier     "HDMI1"
    VendorName     "Unknown"
    ModelName      "Acer 23SH"
    Option         "DPMS"

########### DEVICES ##################

Section "Device"
    Identifier     "Device 0"
    Driver         "intel"
    BoardName      "GeForce"
    BusID          "PCI:0:02:0"
    Screen          0

Section "Device" 
    Identifier     "USB Device 0" 
    driver         "fbdev" 
    Option         "fbdev" "/dev/fb2" 
    Option         "ShadowFB" "off"

############## SCREENS ######################

Section "Screen"
    Identifier     "HDMI"
    Device         "Device 0"
    Monitor        "HDMI1"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24

Section "Screen"
    Identifier     "USB"
    Device         "USB Device 0"
    Monitor        "USB1"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
  • So the regular HDMI monitor is the one that is not working correct?
    – Josiah
    Nov 12, 2012 at 16:39
  • No, the USB-HDMI monitor is the one that doesn't work :). It appears as disconnected even if it is connected and configured in Xorg Nov 14, 2012 at 12:49
  • And you know that this monitor works on other devices or by itself correct?
    – Josiah
    Nov 14, 2012 at 15:35
  • Of course it works, I explained it in the question, when the monitor is set on a single-monitor setting it works, but when it comes to put it with the three monitor setting is doesn't work :) Nov 18, 2012 at 17:50
  • I am not sure what the problem is. But I'll start a bounty and hopefully someone will answer it.
    – Josiah
    Nov 27, 2012 at 14:02

3 Answers 3


I know this should probably be a comment but I only have 46 rep on SuperUser.

I use to get paid to resolve X windows issues and most are not trivial and far to too complicated for this format to resolve. Basically if I wanted to resolve your issue, I would probably need to have a similar setup to test with or work on you system itself. Ian's suggestion of that Matrox TripleHead2Go is a good one.

I will tell you right now if I were building a custom Linux box with triple head support for someone, I would be using at least 2 identical dual head video cards. I don't necessarily need the same video cards but it simplifies things. Now I know with a laptop that is not an option.

First thing you will need to do is show us the xorg log. There's very little chance that we will be able to solve this if we don't know why the usb video card is not working. So the first thing we need to check is the xorg log to see if it can tell us why it's not working or even that it didn't even try to run it.


You might want to consider a solution like the Matrox TripleHead2Go. It has support for DisplayPort monitors, with optional adapters for DVI and VGA monitor support. Matrox have drivers for Linux. It's an expensive solution, but it will take the pain out of your setup.

  • Does it support 1920x1080 resolution? :) Nov 28, 2012 at 10:26
  • Yes. It supports 3x 1920x1080 or 2x 1920x1200 across 2 monitors. And if you ever reinstall the OS or move to another computer, it just works out of the box with minimal setup.
    – Ian Atkin
    Nov 28, 2012 at 16:36


Once the driver is loaded, the DisplayLink monitor is listed as an output provider:

$ xrandr --listproviders

Providers: number : 2
Provider 0: id: 0x43 cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 2 outputs: 2 associated providers: 1 name:Intel
Provider 1: id: 0xcb cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 1 name:modesetting

In the above example, provider 1 is the DisplayLink device, and provider 0 is the default display. Running xrandr --current gives a list of available screens:

$ xrandr --current

Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900       60.0*+   40.0  
   1440x900       59.9  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 disconnected (normal left inverted right x axis y axis)
DVI-1-0 connected (normal left inverted right x axis y axis)
   1366x768       60.0 +
   1368x768_59.90   59.9  
  1368x768_59.90 (0xd0)   85.7MHz
        h: width  1368 start 1440 end 1584 total 1800 skew    0 clock   47.6KHz
        v: height  768 start  769 end  772 total  795           clock   59.9Hz

If the above does not list the DisplayLink screen, then you will need to offload DisplayLink to the main GPU:

xrandr --setprovideroutputsource 1 0

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