Issues with Dual GPU & 4 monitors

oulianotic

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Hey!

First, the classical excuses :
This is my first thread in here so sorry if this is not at the right place, and I also apologize for my english as it is not my first language.

Then a bit of context. I'm new to a company that needs me as a NOC technician. To accomplish my missions, I will have 10 screens in front of me splitted on 2 PCs (6 and 4). I am also the only one that knows a bit of Linux (not debian especially), but well I only had a couple of hours of classes about the classical command lines (cd, cat, grep, cp etc.). So I am just a beginner to Linux and Debian, and I'm kinda lost with my issue.

So, my issue is : how can I make a dual GPU / 4 monitors work on Debian? Even tho no one else knows Linux, they want my monitoring tools to run on Debian specifically.
Specs of GPU and monitors :

2x GPU Nvidia GT 610 (1 VGA + 1 DVI-I)
4x BenQ VW2430

All 4 monitors are using VGA input, 2 of them with a DVI-I -> VGA adapter on the PCs because of the GPUs.
All of it is working fine when taken individually.

I tried for a whole week without great success. I used to mess with the xorg.conf file, and I had different results though the week : only VGA-plugged monitors working, only GPU-1 monitors, all 4 monitors but 2 of them are unresponsive ...

I don't want to spam a thread full of s*** files so I don't really know what to send you for help... I would really like if someone could take some time even over a few days because I have to do other missions at the same time.

Thanks a lot,
 


f33dm3bits

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The max number of monitors I've used on Linux is 3, but I was running it an Intel graphics chip and I would just sort my screens using the display settings. Are you using the nouveau drivers or the nvidia drivers?
 

oulianotic

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I have tried both options : nouveau and legacy-390xx drivers.

When I go to the display settings, it always detects only the 2 working monitors, even in the situation where all 4 are displaying some kind of background but 2 of them are totally unresponsive.
 

f33dm3bits

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I have tried both options : nouveau and legacy-390xx drivers.

When I go to the display settings, it always detects only the 2 working monitors, even in the situation where all 4 are displaying some kind of background but 2 of them are totally unresponsive.
Instead of the display settings from the OS have you tried using nvida-settings, I think you are using debian? And have you checked if the nvidia module is actually loaded via lsmod, and their nvidia documentation may have some useful information.
 

oulianotic

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Yes I did :/

With nvidia-settings, all 4 monitors are detected on 2 different X screens. I don't have any option to change monitors from screen (e.g. moving monitors 3 and 4 to X screen 1 where monitors 1 and 2 are).

Nvidia-detects suggests me to get the legacy 390xx driver (that I am running ATM).
I already tried what is on the documentation you linked me, but didn't fix it.
 

f33dm3bits

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Yes I did :/

With nvidia-settings, all 4 monitors are detected on 2 different X screens. I don't have any option to change monitors from screen (e.g. moving monitors 3 and 4 to X screen 1 where monitors 1 and 2 are).

Nvidia-detects suggests me to get the legacy 390xx driver (that I am running ATM).
I already tried what is on the documentation you linked me, but didn't fix it.
So if I understand you correctly. You are able to move from monitor 1 to monitor 2 and viceversa, but not from monitor 1 and 2 to monitor 3 and 4? And also you are able to move from monitor 3 to monitor 4 and viceversa but not from monitor 1 and 2 to monitor 3 and 4?
 

oulianotic

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Monitors 1 and 2 are functionning perfectly together.
At some point, monitors 3 and 4 were displaying a Desktop interface, but were totally unresponsive (can't open any program on those, right click does nothing, left click on any interface button does nothing too, can't do the "zone select").

ATM, Monitors 3 and 4 doesn't even detect a video input.

Oh and btw, Monitors 1/2/3/4 are not their names via their physical positionning, but by the way Debian detects them.

1 and 2 are always the ones working (even when they are the monitors in physical pos. 3 and 4 working), while 3 and 4 are the ones not working well.

Rn the 2 monitors working are the ones that uses DVI-I to VGA adatper so it looks like this physically :

NOT WORKING || WORKING
--------------------||--------------
NOT WORKING || WORKING
 

wizardfromoz

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G'day @oulianotic and welcome :D

I have to go for my Aussie evening and I have only ever run 2 monitors, but

Code:
xrandr

#and also

man xrandr
may be useful, including output with all monitors attached.

Cheers

Chris Turner
wizardfromoz
 

oulianotic

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I finally made it work!
Idk why it would not before. I inserted a file from another debian computer using multiple display in mine. A bit of manipulations in nvidia-settings later and all my 4 monitors were detected and in the right order.

Thanks for trying to help me @f33dm3bits and @wizardfromoz ! I guess a clean reset of the X Server conf was the way to go.
 

f33dm3bits

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Glad you got it working! :) What you also could have tried was remove or renamed /etc/X11/xorg.conf and then ran:
Code:
nvidia-xconfig
 

f33dm3bits

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Is it supposed to regenerate a default xorg.conf file? I will remember that for the 2nd PC I have to configure! :D
Yes it regenerates the existing xorg.conf file and if it doesn't exist it creates it:
Code:
X11]$ sudo nvidia-xconfig

WARNING: Unable to locate/open X configuration file.

New X configuration file written to '/etc/X11/xorg.conf'
Code:
X11]$ sudo nvidia-xconfig

Using X configuration file: "/etc/X11/xorg.conf".
Backed up file '/etc/X11/xorg.conf' as '/etc/X11/xorg.conf.backup'
New X configuration file written to '/etc/X11/xorg.conf'
 

wizardfromoz

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I love it when they get their own problem solved themselves.

Good on you (goodonyer) @oulianotic :), and good info from @f33dm3bits ;)

Wizard
 


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