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I just updated to 16.04. My system has AMD Radeon HD 5450 graphics card which I use with two 16:9 monitors.

After update, i.e., after removing fglrx, the displays are mirrored and have 4:3 aspect ratio and low resolution. I suspect this has something to do with the driver in use, but I'm unable to change it.

Any suggestions on how to proceed?

$ sudo lspci -v
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cedar [Radeon HD 5000/6000/7350/8350 Series] (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Cedar [Radeon HD 5000/6000/7350/8350 Series]
Flags: bus master, fast devsel, latency 0, IRQ 11
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at fbe20000 (64-bit, non-prefetchable) [size=128K]
I/O ports at e000 [size=256]
Expansion ROM at fbe00000 [disabled] [size=128K]
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Legacy Endpoint, MSI 00
Capabilities: [a0] MSI: Enable- Count=1/1 Maskable- 64bit+
Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [150] Advanced Error Reporting
Kernel modules: radeon

Some other possibly useful information:

$ sudo lshw -c video
  *-display UNCLAIMED     
   description: VGA compatible controller
   product: Cedar [Radeon HD 5000/6000/7350/8350 Series]
   vendor: Advanced Micro Devices, Inc. [AMD/ATI]
   physical id: 0
   bus info: pci@0000:03:00.0
   version: 00
   width: 64 bits
   clock: 33MHz
   capabilities: pm pciexpress msi vga_controller bus_master cap_list
   configuration: latency=0
   resources: memory:e0000000-efffffff memory:fbe20000-fbe3ffff ioport:e000(size=256) memory:fbe00000-fbe1ffff
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  • I fixed a similar issue using xrandr. Execute xrandr to get output infos, max resolution, etc. Then do xrandr --output OUTPUT --mode MAXRES, replacing OUTPUT with the output name of your monitor (cf. the output of xrandr, probably VGA-1 in your case), and MAXRES with the maximum resolution of your screen, as shown using the xrandr command. This should look something like xrandr --output VGA-1 --mode 1920x1080
    – THC
    May 7, 2016 at 9:14

1 Answer 1

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The solution was to remove nomodeset from kernel parameters in grub. This enabled radeon driver and dual monitor setup with correct resolutions was immediately correct after startup.

Unfortunately the radeon driver (and/or perhaps the GPU itself) seems to be little on the slow side with current desktop environments using dual monitor with multiple windows open etc.

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  • This worked for me with amdgpu-pro
    – bradkratky
    Sep 23, 2017 at 4:14

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