Problems with multiple monitors in Ubuntu 13.04

[Dave Airlie]

>
> I have two 6450 cards in my Ubuntu 13.04 system with three monitors. This is
> a recent install with no binary drivers installed and no additional X ppa's
> installed. I can get X to display output on the primary monitor, and I can
> see all three in xrandr:
>
> Screen 0: minimum 320 x 200, current 2560 x 1440, maximum 16384 x 16384
> HDMI-0 disconnected (normal left inverted right x axis y axis)
> DVI-0 connected 2560x1440+0+0 (normal left inverted right x axis y axis)
> 597mm x 336mm
>    2560x1440      60.0*+
> VGA-0 disconnected (normal left inverted right x axis y axis)
> HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis)
> 475mm x 267mm
>    1920x1080      60.0*+
>    1280x1024      75.0     60.0
>    1152x864       75.0
>    1024x768       75.1     60.0
>    800x600        75.0     60.3
>    640x480        75.0     60.0
>    720x400        70.1
> DVI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis)
> 475mm x 267mm
>    1920x1080      60.0*+
>    1280x1024      75.0     60.0
>    1152x864       75.0
>    1024x768       75.1     60.0
>    800x600        75.0     60.3
>    640x480        75.0     60.0
>    720x400        70.1
> VGA-1 disconnected (normal left inverted right x axis y axis)
>
>
> The second and third monitor are on (out of power save mode) but show no
> input. However, XFCE seems to detect them as I have two wallpapers stacked
> on top of each other, one at the main monitor's 2560x1440 resolution and one
> at a 1920x1080 resolution (see
> http://edolnx-public.objects.dreamhost.com/Screenshot%20-%2005072013%20-%2009_10_02%20AM.png
> ). Attempting to make any changes with xrandr causes X to crash with a
> SIGSEGV. Here's a log: http://paste.ubuntu.com/5640585/ Any ideas?

You probably need to setup an xorg.conf like you always have before
for dual-card setups like that.

It might be possible to make it work better if you plug two monitors
into the first card and one into second,
you'll be using GPU offload, so the second GPU won't be doing anything
more than displaying what the first
is showing.

Dave.