Before last weekend, my Debian 8 setup was relatively stable; there were some quirks (like not being able to use accelerated graphics at all), but it was usable for most of what I do. I was using the fglrx driver from AMD for my setup which is the following:

  • ATI Radeon HD 5870
  • 3 identical Samsung SyncMaster SA850 monitors
  • 3 HBR2 DP cables - no dongles or adapters

This worked well, using the full resolution and proper refresh rate for the displays, but I wanted to update to Debian 9, get on the open source driver, and hopefully fix the accelerated graphics issues.

The xserver-xorg-video-radeon driver appears to be working correctly, and identifies the card and the monitors. When I have the system booting into graphical mode, the system actually thinks that everything is fine (gdm3 is running, my applications start up, etc.), but there is nothing on the screens. The monitors complain that "Not Optimal Mode. Recommended Mode 2560x1440" which is the native resolution for the monitors, and what I had been using.

I had initially searched and saw that I could at least get the virtual consoles up and running if I added nomodeset to grub, or set modeset=0 in the kernel module options. However, that basically disables the video driver, and it gives up. Removing that, and leaving modeset enabled, I can use xrandr to change to 1280x1024 and that "works", but it is not the desired setup at all (and doesn't fix the issue with the virtual terminals). I have tried adding a modeline with cvt and xrandr with the exact specifications of the monitor, but that didn't work either. I even tried with 2560x1440 @ 30Hz, and nothing. I tried toggling DPMS. I even tried a "live" Ubuntu USB boot. Nothing.

All packages on the box are updated as of 2018-03-19T14:00Z.

Some package versions, configuration files, and logs.

  • uname: Linux ziggy 4.9.0-6-amd64 #1 SMP Debian 4.9.82-1+deb9u3 (2018-03-02) x86_64 GNU/Linux
  • debian: 9.4
  • xserver-xorg: 1:7.7+19
  • xserver-xorg-core: 2:1.19.2-1+deb9u2
  • xserver-xorg-video-radeon: 1:7.8.0-1+b1
  • firmware-misc-nonfree: 20161130-3


Section "Monitor"
  Identifier  "0-DFP1"
  Option      "TargetRefresh" "60"
  Option      "Position" "0 0"
  Option      "DPMS" "false"
  Option      "Rotate" "normal"
  Option      "Disable" "false"

Section "Monitor"
  Identifier  "0-DFP2"
  Option      "TargetRefresh" "60"
  Option      "Position" "2560 0"
  Option      "DPMS" "false"
  Option      "Rotate" "normal"
  Option      "Disable" "false"

Section "Monitor"
  Identifier   "0-DFP3"
  Option      "TargetRefresh" "60"
  Option      "Position" "5120 0"
  Option      "DPMS" "false"
  Option      "Rotate" "normal"
  Option      "Disable" "false"

Section "Device"
  Identifier "Card0"
  Driver     "radeon"
  BusID      "PCI:6:0:0"

Section "Screen"
  Identifier   "Screen0"
  Device       "Card0"
  DefaultDepth 24
  SubSection "Display"
    Viewport 0 0
    Depth    24
    Virtual  7680 1440

The Xorg.0.log is large (available here) but here are some highlights:

[    10.141] (II) RADEON(0): Output DisplayPort-0 connected
[    10.141] (II) RADEON(0): Output DisplayPort-1 connected
[    10.141] (II) RADEON(0): Output DisplayPort-2 connected
[    10.141] (II) RADEON(0): Output DisplayPort-3 disconnected
[    10.141] (II) RADEON(0): Output DisplayPort-4 disconnected
[    10.141] (II) RADEON(0): Output DisplayPort-5 disconnected
[    10.141] (II) RADEON(0): Using spanning desktop for initial modes
[    10.141] (II) RADEON(0): Output DisplayPort-0 using initial mode 2560x1440 +0+0
[    10.141] (II) RADEON(0): Output DisplayPort-1 using initial mode 2560x1440 +2560+0
[    10.141] (II) RADEON(0): Output DisplayPort-2 using initial mode 2560x1440 +5120+0

Which looks VERY promising, but then this is what seems to kill it:

[    10.253] (II) RADEON(0): Setting screen physical size to 2032 x 381


NOTE: there are NO "EE" lines in there at all.

I have looked at many other threads, have tried using the different 3 ports on the card, using only one monitor, etc.

1 Answer 1


fglrx is no longer supported in Debian 9. Your post appears related to this question previously asked in that they are reporting issues with missing fglrx. I think this forum post has a solution that could work for you. I am including links to the official Debian wiki on how to install open source and proprietary drivers. I recommend you only use the open source drivers.

Use xrandr to Correct Configuration

Delete your old x.org configuration (rm /etc/X11/xorg.conf) and set the output with xrandr.

xrandr -q

If this does not help, I recommend you start from scratch.

Start from Scratch

To make the troubleshooting process smoother let us start by purging all old configurations and drivers. As root(sudo) run these commands:

apt purge "fglrx.*"
rm /etc/X11/xorg.conf
apt install --reinstall xserver-xorg-core libgl1-mesa-glx:i386 libgl1-mesa-dri:i386 libgl1-mesa-glx:amd64 libgl1-mesa-dri:amd64

Make sure your sources.list contains the contrib and non-free repositories like so:

deb http://ftp.us.debian.org/debian/ stable main contrib non-free 

If you needed to add them, do not forget to update apt, simply run as root(sudo) apt update. Next if you choose to use only the open source firmware for your card you will need to run this command:

apt-get install firmware-linux-nonfree libgl1-mesa-dri xserver-xorg-video-ati

And reboot your computer to initialize your graphics drivers and settings.


Please comment with any issues and I can update this answer to try and best correct your issue. Do not forget to reference the wiki on how to remove and install drivers. I believe this post on multi-monitor setups for Debian could help as well. Best of Luck!

  • Thank you for the suggestions, but no luck. I tried both, and still have the same output in the Xorg.0.log, and the same output on the screen. I'm reading the other threads you mentioned, but I believe I had tried most of what is in there. I will keep trying though. If you have any other suggestions, please let me know. (output from xrandr -q is here: xdal.org/~benoit/xrandr.out) Commented Mar 19, 2018 at 18:35
  • Try manually creating an x config like in this guide. This is tricky if reinstalling x and your drivers did not correct the issue.
    – kemotep
    Commented Mar 19, 2018 at 19:07
  • Sadly, nothing worked. I gave up and bought a new video card. I got myself a Radeon RX 570 and it pretty much worked right away (a bit of tweaking to change from radeon to amdgpu, but that was all). It still sucks that I had to spend quite a bit of money to get this to work, but at least I can work again. Thanks for all the suggestions. Commented Mar 21, 2018 at 3:32
  • Did anyone had success on using the radeon driver module on stretch? I have a Radeon HD 4350/4550 and had no luck like David. I think, this module simply is broken....
    – Nicolas
    Commented Apr 21, 2018 at 9:54
  • @Nicolas, I am currently using the latest radeon drive module but for my RX 480. According to the documentation your card should be supported. what is the output of glxinfo | grep "OpenGL renderer"?
    – kemotep
    Commented Apr 23, 2018 at 15:48

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