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Old 01-30-2013, 06:03 AM   #1
Philosopher
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How to set up 3 monitors?


Hi everyone,

I just set up a new workstation with 3 Monitors, but for some reason it's not possible for me to make all monitors work. While two is no problem, the third one is really stubborn.

OS: Fedora 18 x64 (fglrx, catalyst 13.1)
Graphics: Radeon HD 5770
Monitors: 3 Flatscreen of the same type (connected to DVI / DVI / DisplayPort)

I tried
Code:
aticonfig --initial -f --dtop=horizontal --overlay-on=1
which generated an xorg.conf that didn't work (only two of three). I tried editing it manually also as using the catalyst control center and even via gnome-control-center, removed th xorg.conf and started over - nothing. The closest I got was when I tried to activate the third monitor in catalyst and it said "not possible due to not enough videomemory". So I double checked the specs of the graphicscard vendor, which says:
Quote:
ATi Eyefinity Technology
- Support up to 3 monitor outputs simultaneously and independently.(one of the outputs must be DisplayPort.)
- Maximum 3 * 2560*1600 resolution.
So it must be possible, right?

Output of xrandr:
Code:
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 1920 x 1920
DFP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      59.9*+   50.0     59.9     30.0     25.0     30.0  
   1776x1000      50.0     59.9     25.0     30.0  
   1680x1050      50.0     60.0  
...
DFP2 disconnected (normal left inverted right x axis y axis)
DFP3 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      59.9*+
   1680x1050      60.0  
...
DFP4 connected (normal left inverted right x axis y axis)
   1920x1080      59.9 +
   1680x1050      60.0  
...
CRT1 disconnected (normal left inverted right x axis y axis)
CRT2 disconnected (normal left inverted right x axis y axis)
So, if anybody knows how to make this work - any help is really appreciated!
 
Old 01-30-2013, 09:12 AM   #2
jwhitworth
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Which of the three monitors is not working correctly? Is it the one that your running from the display port? Do your monitors support input from a display port? If your using a cable to convert from display port to dvi that could be your issue. I'm getting ready to put together a 4 monitor setup running off of a 6870 so I've been doing some research and from what I've read if your monitors do not natively support input from a display port then you need to run a powered converter which converts the signal from the display port to a signal which can be interpreted by a dvi port such as: This Here
 
Old 01-30-2013, 10:51 AM   #3
Philosopher
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I can get all monitors to work, just not all at the same time. E.g. i can run the monitors at the DisplayPort and one of the DVI or both DVI.

The DisplayPort is being converted to HDMI (to DVI didn't work at all). I'm not sure if the converter is 'active', but since xrandr is able to identify all monitors it should be ok the way it is, shouldn't it?
 
Old 02-05-2013, 08:47 AM   #4
jwhitworth
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Quote:
Originally Posted by Philosopher View Post
I can get all monitors to work, just not all at the same time. E.g. i can run the monitors at the DisplayPort and one of the DVI or both DVI.

The DisplayPort is being converted to HDMI (to DVI didn't work at all). I'm not sure if the converter is 'active', but since xrandr is able to identify all monitors it should be ok the way it is, shouldn't it?
If all the monitors are being identified you wouldn't need an active converter...so hardware wise you should be alright. Here's a thread I started on debian forums about multiple monitors...maybe it can help: http://forums.debian.net/viewtopic.php?f=5&t=91176
 
Old 02-06-2013, 04:51 PM   #5
Philosopher
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I got it working, finally! And, yes, it looks like the passive Display Port converter was the one to blame. I ordered an active on and after tweaking a little bit here and there it's done: 3 monitors working simultaneously even with xinerama!

Most was done via Catalyst Control Center, however, first I had to manually assign the virtual desktop size by creating a file "/etc/X11/xorg.conf.d/01-virtual-desktopsize.conf":
Code:
Section "Screen"
        Identifier "amdcccle-Screen[1]-0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Virtual   5760 1920
                Depth     24
        EndSubSection
EndSection
Not til then it was possible to configure monitors and xinerama.

One final note about active and passive Display Port converters: While fglrx (Linux and Windows) needs an active adapter, the radeon driver also managed it with the passive one.

Thanks again for the hint!
 
  


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