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I finally found a low-power graphics card with four outputs capable of driving 2560x1440 monitors. And it mostly works, except for one important thing: in Fedora 16 (using the standard Gnome environment), when I enable all four monitors, or three if they are arranged lengthwise, the Xorg X11 server dumps core right away and I end up back at the login screen. This happens when I use the Display applet under System Settings.

I can enable two 2560px-wide monitors side-by-side. I can do four at half-resolution. I can do three vertical (so each is 1440px wide). I can even do 3x 1440px wide plus one 720px wide, I think. But 4x 1440px crashes X right after I click Apply, as does a 2x2 grid of 2560x1440.

This leads me to wonder if there is some sort of limit on the total number of pixels either linearly or in area. It seems like there is, and that the limit might be around 5200px wide or 12Mpx total.

I'm using the free xorg-x11-ati-drv package, and the current stable packages in Fedora 16. The computer has 16 GB of RAM.

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No, Gnome just got stupid in F16 (maybe F15). – Ignacio Vazquez-Abrams Mar 22 '12 at 3:47
Are you saying this from experience? Do you have a link to a bug report by chance? Or are you speculating that it broke recently and used to work? I should have mentioned that I am using Forced Fallback Mode so my Gnome Shell looks like the "old" one from F15, even if it's running the current code. I don't know if that matters at all, but I should try it the other way. – John Zwinck Mar 22 '12 at 9:59
Alls I know is that my multimonitor (external monitor, but same difference) setup was fine in F14, and then when I upgraded to F16 everything went pear-shaped. I have also heard others' experiences with the same, but I'm afraid that I can't point you to any specific references. – Ignacio Vazquez-Abrams Mar 23 '12 at 6:07
up vote 0 down vote accepted

Eventually this sort of started working, without me doing anything really. Then at some point it stopped working again. I'm back to three monitors. Hopefully it will get fixed in the future as people get larger desktop resolutions on their workstations, but for now it seems like a lost cause on Linux.

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...but for now it seems like a lost cause on Linux. You mean, in Gnome. Because this guy seems to have more then four monitors up and running. On a more serious note, did you try to mass around directly with xrandr? – Bobby Sep 20 '12 at 7:50
The problem doesn't even seem to be exactly the number of monitors, but their total resolution. Note that many workstations you see with 5-8 monitors still have similar or smaller total pixel resolution compared to mine. Maybe it is somehow a Gnome thing, but I really think it's something broken in Xorg and/or the drivers for ATI. Anyway, no, I did not try messing around with xrandr. I wouldn't know where to start. – John Zwinck Sep 20 '12 at 14:08

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