Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

As we are all painfully aware, the only way to get multiple monitors AND compositing (Compiz) on Linux is to use a single graphics card that can drive both (or in my case all three) screens.

I bought a Radeon 5750 specifically because it claims to able to drive 3 monitors. I can plug in 3 monitors (2 DVI, 1 HDMI) and the Catalyst Control Center shows all 3, but only 2 can be enabled at a time.

The exact message is:

The current settings cannot be applied.  Possible issues may include:
   - Display(s) cannot be enabled.
   - Setting(s) cannot be applied due to insufficient video memory.

So I'm going to assume that either the 5750 doesn't support 3 monitors, OR, more likely, ATI couldn't be bothered to add that support to their Linux drivers.

So this is a multipart question:

First, can anyone suggest a PCI Express Graphics card that can run 3 screens on linux without tremendous pain? I'm looking for something where you install the driver and all three screens "just work". Does such a card exist?

Second, if you have a 5750, have you been able to get it to do 3 monitors?

I'm running Ubuntu 10.04 at the moment.

UPDATE:

I got my active adapter in the mail today (it's DisplayPort to DVI) and so far things seem to be better. I can run my third screen, drag things seamlessly between them, and I am also running compiz. The adapter I'm using is a "B087B-005B" made by "Accell", UPC is "826388106239".

There's still a couple "annoyances" that need worked out though:

The left most screen is always the primary monitor. Which means the "gnome bar" (is that what you call the applications-places-system menu?) is always on the left most screen.

It also means that new dialogue boxes always opened centred on the left screen, which is counter intuitive. Especially if you're using a program like GIMP and the text editor or color picker pops up on the left. Does anyone know of a way to change it so that new windows always pop up on the center screen?

share|improve this question
add comment

3 Answers

up vote 5 down vote accepted

I believe that you need to have one of the displays connected through an active adapter, as the cards that are on sale today do not have enough power to support 3 displays at once (power-wise); or to be more specific, with the exception of some models, they don't have the necessary hardware to power 3 ports.

The following forum threads may provide more insight:

The latter two are well known hardware focused websites, so they should be reasonably reliable (considering them being forums and not official articles). However please note that I don't have an ATI Eyefinity-capable card, nor have I tried this kind of thing under GNU/Linux yet. I'm only sharing what I've read elsewhere in the past, hoping that it can guide you in the right direction (or that somebody else confirms it).

Edit:
The following support article claims that 3+ monitor configurations require to have the extra monitors on top of the base two connected via DisplayPort:

You mentioned that you have the monitors plugged-in via 2 DVI and 1 HDMI ports. Do you have the option to try switching one of them to DisplayPort and giving it a try?

share|improve this answer
    
I guess I can't edit my comments on this site? Anyway... Can I use a passive "Display Port" adapter? Or does it need to be an active one? Does anybody have one known to work well? Also, I'm not sure I understand the difference between "dual-link" and "single link". –  N Rahl Jan 5 '11 at 9:32
    
I bought an DisplayPort to HDMI adapter, but I'm still getting the same error message as above when trying to enable the 3rd display. –  N Rahl Jan 5 '11 at 18:04
    
Regarding Single-/Dual-link DVI - the Dual-link one contains more connectors/wires which can be used to transfer the video signal, thus allowing to transfer more data over the interface - e.g. for achieving higher resolutions or refresh rates. –  MicE Jan 6 '11 at 14:49
    
Regarding the adapter - ok, so you now have 2 displays connected via DVI and one via DisplayPort-to-HDMI adapter? That should have done the trick if the source of the issue were the ports (it might have helped anyway, but it dies not seem to be the root cause). Can you specify the model of your graphics card (on top of 5750) and which driver version you are using please? Unless anyone has better advice, I'd suggest also trying to ask on the official AMD and Ubuntu forums. –  MicE Jan 6 '11 at 15:08
    
@N Rahl: It must be an active adapter, see my reply. –  j-g-faustus Jan 6 '11 at 15:38
show 1 more comment

Maximum two monitors can be enabled at the same time over the DVI and HDMI ports.

To use three monitors, at least one of them must use the DisplayPort.

From AMD Eyefinity FAQ:

How many non-DisplayPort monitors can I use with an AMD Eyefinity technology-enabled graphics card?

You can connect up to two non-DisplayPort monitors at one time to an AMD Eyefinity technology-enabled graphics card using non-DisplayPort connections or passive DisplayPort dongles. To enable and drive 3 or more non-DisplayPort monitors at one time, the additional non-DisplayPort monitors must be connected with an active DisplayPort dongle.

AMD also has a list of working adapters for running non-DisplayPort monitors off a DisplayPort.


On Linux support

A post on phoronix.com says that AMD has Eyefinity support for Linux from driver version 10.7 of July 2010, and that Ubuntu 10.04 has "production support".

However, the AMD Eyefinity FAQ merely says that

There are plans for Linux support in an upcoming update to AMD Catalyst™ software

and the official ADM Eyefinity Technology page says (tiny font at the bottom) that

  1. ATI Eyefinity technology can support up to 6 displays using a single enabled ATI Radeon™ graphics card with Windows Vista or Windows 7...

  2. ATI Eyefinity technology can support multiple displays using a single enabled ATI FirePro™ professional graphics card... Microsoft® Windows® 7, Windows Vista®, or Linux® is required in order to support more than 2 displays.

So the official stance seems to be that multiple displays for Linux is only supported for their professional cards.

The Unofficial AMD Linux wiki says in an entry added December 2010:

The proprietary driver supports more than two simultaneous outputs on HD5xxx cards having more than two physical independant out...

EyeFinity support is still messy

share|improve this answer
    
I'm currently running Catalyst 10.12. I've ordered an active adapter so we'll next week if it's going to work or not. –  N Rahl Jan 8 '11 at 5:37
    
Good luck! Considering the same setup myself (Ubuntu 10.10 and three monitors), guess I'll wait to hear how it works for you first :) –  j-g-faustus Jan 8 '11 at 9:51
add comment

I am using a 5450 with 3 monitors (one on dp) and it works flawlessly with windows 7. When I run the Ubuntu 11.04 CD, I am having trouble with the dp monitor rendering properly, but they are all three working side by side. You must have a dp adapter that says "eyefinity compatible"

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.