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  • Originally posted by bridgman View Post
    Most of the problems I have seen with 2 monitor systems come from not running "aticonfig --initial=dual-head" during installation.
    Uh, that configures zaphod mode, doesn't it? Does anyone still use that?

    I prefer xrandr-style, so I just put a simple xrandr command in my startup:
    xrandr --output DFP3 --primary --auto --pos 0x0 --output DFP4 --auto --right-of DFP3

    (although I'm sure a few of those options are redundant )


    Originally posted by mugginz View Post
    Eyefinity is the obvious choice as a solution.
    not supported by fglrx yet, unfortunately. Haven't seen an official ETA yet, either, other than "in an upcoming release".

    When I plug in three monitors, only two light up, even though randr will happily announce that all three are working.

    Dual monitors have worked in fglrx for as long as I can remember, though.

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    • Originally posted by mugginz View Post
      ATI stable where nVidia isn't? Not a very common outcome there.
      same here, but mostly because nvidia used to crash randomly all over the place while fglrx only crashed during guildwars/wine.

      so I started dual-booting for guildwars and haven't had a crash since. At least I can get my work done without hard lockups.

      (other wine programs, like snex9x or VBA with opengl-output, were stable until now. It seems that only complicated 3d-apps on wine are problematic.)

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      • Originally posted by rohcQaH View Post
        Uh, that configures zaphod mode, doesn't it? Does anyone still use that?

        When I plug in three monitors, only two light up, even though randr will happily announce that all three are working.
        Not sure about zaphod mode (the init string is just what the fglrx devs recommended when I asked about people having trouble with dual screens), but it did seem to make the difference between "not working" and "working" for a number of users.

        Is one of the three monitors connected via display port ? The HD5xxx cards have many CRTCs but only have two independent pixel clock generators, so you can have up to two conventional screens plus additional display port screens.

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        • Originally posted by bridgman View Post
          Is one of the three monitors connected via display port ? The HD5xxx cards have many CRTCs but only have two independent pixel clock generators, so you can have up to two conventional screens plus additional display port screens.
          Indeed. I unfortunately would need to acquire an active dongle in order to support my third screen when Eyefinity comes to Linux. US$100 is a bit steep though. Would probably rather put that $100 towards a six port Eyefinity card though if it meant I didn't need the active dongle for three screens.

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          • I got the impression that active dongles were only needed for the higher resolutions (ie dual-link territory). Don't take that as gospel though...

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            • Originally posted by bridgman View Post
              I got the impression that active dongles were only needed for the higher resolutions (ie dual-link territory). Don't take that as gospel though...
              I'm lead to believe that you need the dongle for more than two DVI monitors. I need to drive three 1920x1200 screens via DVI. Two DVI and one Display-port is doable without the dongle though.

              If you have better info though I hope you're right.

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              • Originally posted by bridgman View Post
                Is one of the three monitors connected via display port ? The HD5xxx cards have many CRTCs but only have two independent pixel clock generators, so you can have up to two conventional screens plus additional display port screens.
                right, ignore my last post.

                My situation is a bit more complex: I have two monitors (both DVI) and a projector (HDMI). I don't need the projector when using the monitors and vice versa, so two outputs at a time would be plenty.

                Unfortunately fglrx seems to permanently disable DFP4 (dvi#2) when it detects a cable in DFP2 (hdmi), no matter if there's actually a picture on DFP2 or not. To use the second monitor, I have to unplug the projector before the system boots (though thankfully that can be done at the projector, I don't have to switch cables under my desk any more).

                I'm hoping this configuration will magically start working once eyefinity is officially supported. If it doesn't, I'll wait for the OS drivers and (try to ) make it work.
                In any case, it's just a minor inconvenience, nothing I'd consider buying a >50? DP-adapter for.

                Originally posted by bridgman View Post
                so you can have up to two conventional screens plus additional display port screens.
                wait, multiple DP screens? That's limited to the 6-DP-Eyefinity edition, isn't it?

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                • Originally posted by rohcQaH View Post
                  wait, multiple DP screens? That's limited to the 6-DP-Eyefinity edition, isn't it?
                  It depends what connectors the OEMs put on their boards. Generally, most seem to be 1 DP and several non-DP outputs for a total of 3 possible independent screens, but you could in theory design a board with more 2 or more DP outputs and some combination of non-DP ports for between 2 and 6 independent screens. However, as you add more possible simultaneous screens, you need more memory bandwidth, so that needs to be taken into account when designing the board. A lot of current boards have 2 dual-link DVI ports, an HDMI port, and a DP port. That combination uses all the possible outputs, so you'd have to give up one of those to add another DP port.

                  The hardware has 2 PLLs, 6 crtcs, 2 DACs, and 6 digital transmitters (which can be used for LVDS/TMDS/DP/eDP/HDMI). DP runs at a fixed clock, so you don't need a separate PLL for it. That gives you some combination of up to 2 non-DP outputs, and up to 6 DP outputs for a maximum of 6 possible independent screens. Dual-link DVI ports require 2 digital transmitters (one for each link), so a dual-link DVI port would use 2 of the 6 possible transmitters, leaving 4 for other digital outputs. Two dual-link DVI ports would use 4 digital transmitters which would leave 2 for other digital outputs.

                  DP only requires 1 transmitter. So in order to use a dual-link DVI monitor on a DP port, you need an active converter since native dual-link is not possible due to the lack of a second transmitter when running in DVI pass-through mode.

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                  • Originally posted by bridgman View Post
                    None of the distros we support use X-Server 1.7, do they ? Would it be more correct to say that your complaint is "we don't officially support all distros with fglrx (some are open source driver only right now), and on some of those unsupported distros there is a problem with X-Server 1.7" ?
                    You tell me.

                    Checking distrowatch, Debian, Ubuntu and Mandriva, for examples, seem to agree that X-Server 1.7.5 is stable. Can there still be problems? I don't know. What is their definition of stable?

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                    • Of the three distros you listed, only Ubuntu is on the "official support" list and the latest release (Karmic) uses 1.6.4 according to distrowatch (my system is 1.6.3, thought it was up to date ???).

                      The references to 1.7.5 are for development builds of Lucid, which has not yet been released.

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