3 Displays Ubuntu, ATI Radeon

Question

There are lots of questions on this but I've read them all and none helped me!

• ATI Radeon HD 5400 Series

• PCI Express 2.0

My co-worker attempted to use 3 displays on windows, that failed...

However he managed to get 3 displays on ubuntu using the exact same graphics card as me!

I know its possible!

• Display One: 22" DVI

• Display Two: 22" VGA

• Display Three: 19" VGA

My graphics card has: HDMI, DVI, VGA.

• The HDMI goes to Display One using a HDMI to DVI converter

• The VGA goes to Display Two directly

• The DVI goes to Display Three using a DVI to VGA converter

When I open ubuntu display settings, i see the 3 displays, however Display Three is set to OFF by default... When i try to enable it, my PC does nothing!

When I open Catalyst Control Center, i see the 3 displays again, but the 3rd is set to "disabled" and I cannot enable it...

What do i need to do?

Answer 1

Before we start, sometimes the HDMI port is pushed by the same hardware that pushes DVI/VGA so it might be that you need three 'real' ports not a port that works if and only if the other is disabled.

To find out if the previous is the case, disable your second monitor and see if the HDMI is enable-able then. If it is, then it's the case. If it still isn't then keep reading...

Mine is 2 DVIs and a displaylink port.

I currently have this working without 3D support using Xinerama like this:
xorg.conf

Section "ServerLayout"
    Identifier     "aticonfig Layout"
    Screen      0  "aticonfig-Screen[0]-0" 0 0
    Screen         "aticonfig-Screen[0]-1" LeftOf "aticonfig-Screen[0]-0"
    Screen         "aticonfig-Screen[0]-2" LeftOf "aticonfig-Screen[0]-1"
EndSection

Section "Module"
EndSection

Section "ServerFlags"
    Option      "Xinerama" "on"
EndSection

Section "Extensions"
    Option      "Composite" "Enable"
EndSection

Section "Monitor"
    Identifier   "aticonfig-Monitor[0]-0"
    Option      "VendorName" "ATI Proprietary Driver"
    Option      "ModelName" "Generic Autodetecting Monitor"
    Option      "DPMS" "true"
EndSection

Section "Monitor"
    Identifier   "aticonfig-Monitor[0]-1"
    Option      "VendorName" "ATI Proprietary Driver"
    Option      "ModelName" "Generic Autodetecting Monitor"
    Option      "DPMS" "true"
EndSection

Section "Monitor"
    Identifier   "aticonfig-Monitor[0]-2"
    Option      "VendorName" "ATI Proprietary Driver"
    Option      "ModelName" "Generic Autodetecting Monitor"
    Option      "DPMS" "true"
EndSection

Section "Device"
    Identifier  "aticonfig-Device[0]-0"
    Driver      "fglrx"
    BusID       "PCI:1:0:0"
    Screen      0
EndSection

Section "Device"
    Identifier  "aticonfig-Device[0]-1"
    Driver      "fglrx"
    BusID       "PCI:1:0:0"
    Screen      1
EndSection

Section "Device"
    Identifier  "aticonfig-Device[0]-2"
    Driver      "fglrx"
    BusID       "PCI:1:0:0"
    Screen      2
EndSection

Section "Screen"
    Identifier "aticonfig-Screen[0]-0"
    Device     "aticonfig-Device[0]-0"
    Monitor    "aticonfig-Monitor[0]-0"
    DefaultDepth     24
    SubSection "Display"
        Viewport   0 0
        Depth     24
                Modes "1440x900_60.00"
    EndSubSection
EndSection

Section "Screen"
    Identifier "aticonfig-Screen[0]-1"
    Device     "aticonfig-Device[0]-1"
    Monitor    "aticonfig-Monitor[0]-1"
    DefaultDepth     24
    SubSection "Display"
        Viewport   0 0
        Depth     24
                Modes "1440x900_60.00"
    EndSubSection
EndSection

Section "Screen"
    Identifier "aticonfig-Screen[0]-2"
    Device     "aticonfig-Device[0]-2"
    Monitor    "aticonfig-Monitor[0]-2"
    DefaultDepth     24
    SubSection "Display"
        Viewport   0 0
        Depth     24
                Modes "1440x900_60.00"
    EndSubSection
EndSection

with binary driver...

Where is xorg.conf: /etc/X11/xorg.conf
What is xorg.conf: It's a way to tell your computer 'No do not auto configure...I know better. Do it like this:'

Answer 2

I know this is an old question, but I have exactly the same setup as you, and have been running into the same problem. I figured I'd share this here, since it hasn't been discussed anywhere else.

The problem seems to be the proprietary AMD driver in combination with certain older GPUs, rather than any particular X settings. Since these cards only use two pixel clocks, I suspect some combination of lazy coders and stingy testers blocked the use of three displays in their driver, rather than build a workaround to allow the sharing of two pixel clocks among three displays.

A simple fix for you is to open the command line and run:

sudo apt-get remove --purge fglrx*

This removes the AMD driver, along with Catalyst Control Center, and forces Ubuntu to use the Linux Radeon driver instead. You should still be able to configure the display settings using the Ubuntu display manager, instead of fiddling with xorg.conf.

Although the open-source driver lets you use three displays, you will need to set at least two of your monitors to the same resolution and refresh rate (there's no possible way to get around this: different resolution/refresh rate=different pixel clock speed). Unfortunately, I've had problems with any setup other than all three matching. This limits you to the settings available on your lowest-resolution display. You also lose out on any 3D acceleration features provided by the AMD driver.

Answer 3

Even though this is a few years old, I see there is no accepted answer. I have a Sapphire Radeon HD 5450 card that drives three monitors. My monitors are VGA 1440x900, HDMI 1680x1050, and VGA 1440x900. The ports are VGA, HDMI, and DVI. Therefore, for the DVI port I use an adapter. You would need to use the open source xorg drivers for best results. No xorg.conf was necessary. In Xubuntu I had to fiddle in Monitor Preferences a bit, but it works great. Each monitor is at its native resolution. In Xubuntu in Monitor Preferences, I disabled all monitors but the far left one. Then I configured the far left how I wanted it. Then I enabled the middle monitor and configured it. Then I enabled the far right one and configured it. You will need to set the card as primary in BIOS. This only worked for me in 14.04, not 12.04. Linux Mint 17 also works with this.

Answer 4

My Radeon HD5450 has HDMI, DVI and VGA outputs and I was also running into the same problem of only being able to run 2 monitors in any combination. I spent ages trying to get it to work but no matter what I did one of the monitors was always disabled even though all 3 were detected. I then tried the solution proposed by col_panic:

sudo apt-get remove --purge fglrx

It worked - now all three monitors are working just great. (2 at the same resolution and 1 smaller monitor at a lower resolution) Thanks col_panic for taking the time to post this - I couldn't have done it without you. :)

Answer 5

I've been using Nvidia GeForce GTX 1650 OC 4GB GDDR6 with 3 monitors: Left: 1920x1080 flipped vertically, middle: 2560x1080, right: 2560x1080 for 20 days now. I noticed that trying to install NVidia driver 470 would result in unmet dependencies error: sudo apt install nvidia-driver-470; I installed driver 515 and it has caused Youtube and Netflix video on Chrome 105.0.5195.125 to lag or pause for 0.5 second every 10 seconds. Also lagged on Firefox. It's frustrating as audio does not lag or pause. I install driver 520 and rebooted. So far the lagging does not happen. I had to disable hardware acceleration in Chrome;otherwise, Chrome would freeze up once every 3 days. However, the open source Chromium does not freeze up with hardware acceleration turned on.

I also noticed that clicking on the Chrome tabs would become unresponsive after leaving the logon session on for over 2 weeks. A quick fix is to kill gnome-shell process which makes the desktop shell disappear for 5 seconds and re-appear. I don't see any of the problems on a AMD RADEON PRO WX 2100 2GB GDDR5 PCIE card but that card can only connect 2 monitors at 1920x1080 regardless which 2 out of 3 ports I use. I'm running Ubuntu 22.04.1 LTS on kernel 5.15.0-47-generic #51-Ubuntu SMP.

On a different PC, I installed the SAPLOS Radeon HD 5450 Graphics Card,2GB,GDDR3,with DVI,HDMI,VGA outputs. All 3 monitors of 1920x1080 have content but the DVI and VGA have identical content. Ubuntu settings show 3 displays 1,2,3 but the VGA and the DVI connected monitors have the same display number. I don't have any package of fglrx installed during the whole experiment.

Back to the primary PC, I replaced Nvidia GeForce GTX 1650 with MAXSUN AMD Radeon RX 550 4GB GDDR5 hoping to get hardware acceleration in Chrome to work natively without freezing. It turned out to be very disappointing. The card recognizes all the displays but the 2560x1080 display that connects to the DVI port via a DVI-HDMI adapter can't get the resolution right. The text is blurred and the monitor complains about mismatching resolution. I switched the cables around but somehow the DVI port does not like the ultrawide display. I had to give up and return on Amazon.