Multiple Video Outputs
A rather neat way these days to expand the functionality of your Linux Desktop is to spread the Desktop screen itself across several monitors. There are many ways to achieve this and one of the ways we will discuss here in this article. Dual screens are not that uncommon now days even for Ubuntu(Linux), Windows and Mac, this article however will be dealing with the configuration of a Quad Monitor display output.
You will need to consider what it is that you require from your monitor outputs, by that I mean screen resolution, aspect ratio and refresh rates. To identify these you will need to consider the specifications of the monitors you intend to operate with your Video card, then find a card that will manage the number of ports you need at the resolution etc you require.
There are many graphics video cards on the market and nearly all PC clones with a relatively new motherboard will use a PCIe (Peripheral Component Interconnect Express) X16 slot. With only one PCIe slot you can only fit one card and usually this is adequate for most jobs as people seldom need more than two monitors. However if you need more monitors you need more specialised cards that fit in the one PCIe slot. If you are considering the addition of another video card on your motherboard it is strongly advised that these be of identical types and models.
There are essentially three different PCIe slots the x4 the x8 and the x16 and should not be confused with PCI-X which is the (Peripheral Component Interconnect eXtended). This is a less common slot usually found in servers rather than PC’s and PC clones.
The card we have chosen for the purposes of this article is the PCIe X16 NVS Nvidia 450 256Mb Ram at a cost of £160 this is not a cheap card, but it will do 1024 x 768 pixels and has the four standard VGA 15pin D-type via two splitter cables especially adapted for the video card. Alternatively you could choose the NVS 420 with 512Mb Ram but whilst this uses the same or similar splitter the four DVI outputs are a little special. These four outputs are called DVI-D and standard DVI cables do not fit in them, only DVI-D male connectors will fit in them trust me I have wasted many hours looking for the right cables, if you think you can use adapters on them to convert from DVI to VGA you can’t the standard converters, to differentiate the standard DVI have four pins two each side of the blade the DVI-D has no pins just the blade.
Installation of the card was extremely simple the dual graphics card that was installed was removed and the alternative NVS Nvidia 450 put in its place. Once the card was secured by way of a small retaining screw then both adapters were fitted dangling from the card outside the case.
Software and Operating System
We will be using Ubuntu with this installation and the recommended drivers identified via the “Additional Drivers” section of your System Administration menu options.
For this installation we used the 10.10 version of Ubuntu which is now out of current circulation as this still used Gnome as a standard display before the later versions adopted Unity in preference. We used the 64 Bit variant as our PC could support this CPU architecture, however the procedure outlined should work equally well for 64 and 32 Bit.
Once your Operating System is installed (Ubuntu or some variant thereof) select “System” from the Menu then “Administration” and finally “Additional Drivers“. Locate the Recommended drivers for the card detected and install them. Now reboot for the changes to take effect
Our system setup is as follows:-
- PC with standard AMD 64 Bit uProcessor and one PCIe x16 slot
- NVidia NVS 450 256mb Ram PCIe x16 four VGA ports (Graphics Card)
- Two VGA spliter adaptors for the aboove card
- Ubuntu Ver 10.10 64 Bit OS
- Four HP L1530 Monitors Max resolution (1024 x 768)
The purpose of this configuration is to extend a single desktop across four individual screens that will enable us to place any application run from the Desktop Menus or consoles anywhere in or between the displays configured
For your consideration I have attached below two configuration files that need to be renamed “xorg.conf” before you use either of them. One configuration setup is for a three screen display the other is for a four screen display. Please feel free to use or view the configuration examples to help you format your own displays.
When you have installed all of the above and updated as necessary you should follow the procedure below:-
- Open a new console and type the following commands
- What we aim to achieve here is to backup the orginal xorg.conf so if we get into trouble we can recover to a known working state, then we want to enable all the GPU on the graphics card before we can configure the screens. This is what
“nvidia-xconfig -a” will do create a new xorg.conf and enable all the GPUs on the NVidia card we are using.
- Reboot the computer for the new configuration to take effect
- If the desktop has not started just login as usual on the command using you login username and password, recover the original xorg file and rename it xorg.conf in /etc/X11 directory, retry the above steps
- If you can login to your desktop well done we can proceed to the next step, locate and access the application
“NVIDIA X Server Settings” this is in System, Administration section of your menus.
- You should see in the list both GPU listed and any monitors attached
- Locate and access from the list “X Server Display Configuration” this will display the monitors enabled or disabled on the current system
- One screen at least possibly two will be active for sure make sure you can move the cursor between the screens do not enable “Xinerama” just yet use the “Save to X Configuration File” just above the “Quit” button on the panel. Save the configuration file as “xorg-2screen.conf” and commit to save the file in “/etc/X11 directory you could also save the files to their own directory however in both cases you will need to be the administrator with root or super user privileges.
- Be persistent and one at a time activate all thee screens saving the “xorg.conf” each time you add a screen.
- Once all screens are active enable “Xinerama” again this may take some persuasion but if you have doubts edit xorg.conf and look for ” Option “Xinerama” “1” ” in the Server Layout section of xorg.conf if the vaule is 1 then Xinerama is set if it is “0” reset this value to “1”