Quad Monitor with Dual 7800GTX?

[aesaeion]

I am looking into getting two 7800GTX cards here soon and I wanted to know if I could drive 4 lcds at 1920x1200 each using the proprietary nvidia driver. I would like opengl hardware accel to work across all 4 monitors. My experience with the ati driver has been pretty bad in that I can't get it to initialize more then 1 radeon card in a machine at a time so I wanted to know what problems I could expect doing it with nvidia cards instead.

The motherboard I plan to use is a tyan k8we board.

Under windows I only care if 1 monitor works since I will just use one of the monitors for games but I want all 4 to work under linux and would prefer that all are hardware accelerated.

[JaXXoN]

Hi!

I successfully tested several quad-head configurations with four 1600x1200
LCDs, i.e. 4x1 and 2x2 (find a bunch of example xorg.conf files attached).
Concerning 1920x1200, AFAIK, the second DVI output on any 7800GTX card
is only a single link DVI, but that should be sufficient for that resolution.
Please note that the resolution for OpenGL applications is limited to
4096x4096 pixel - the actual desktop can be bigger than that (i.e. i'm
using a 4800x1200 desktop with three 1600x1200 LCDs), but if you make
a 3D application window bigger than 4096 pixels (width/height), then the
windows stays black. I tested a 2x2 LCD setup with a combined resolution
of 3200x2400 pixel in xinerama mode with glxgears. 3840x2400 should work,
too. For full screen gaming, i'm using a 3840x1024 (3x 1280x1024) tripple
head setup in order to stay below the 4096 pixel limit.

regards

Bernhard

[aesaeion]

Thank you very much. I have looked at the configuration files and they look very useful also. However I have a question. What is the difference between
xinerama-dualview-dualview, xineram-twinview-twinview and multiscreen-dualview-dualview? Just want to know the pros and cons so I can figure out which setup will work best for me.

[JaXXoN]

Originally Posted by aesaeion

What is the difference between xinerama-dualview-dualview,
xineram-twinview-twinview and multiscreen-dualview-dualview?

"dualview" means that the two outputs on one card are configured
as two seperate physical screens (i.e. :0.0 and :0.1m check section
"P. Configuring Multiple X Screens on One Card" in the driver README)
while "twinview" means that the two outputs make up a single physical
screen spanning two physical dispalys (check section "G. Configuring
TwinView" in the driver README). Unless you have special requirements,
you will probably prefere twinview over dualview: dragging windows
between seperate screens is slower than between twinview screen,
because the Xserver (xinerama mode) or the window manager
(multiscreen mode) needs to take care about spliting the window
and drawing it on seperate physical screens while with twinview, there is
only one physical screen (spanning two displays).

"xinerama" means that several physical screens will be combined to
one big logical single screen while "multiscreen" will keep seperate screens.
With Xinerama, the Xserver will take care about splitting windows
to several screen while in mutliscreen mode, the window manager
will need to do it (if capable at all). Unless you have special requirements,
you will probably prefere xinerama over multiscreen.

With xinerama, you can easily move windows between each display
by just dragging them with the mouse since the whole setup looks
like a single screen for the window manager and the applications.
potential drawback: if you maximize a window, it will span the whole
desktop, not only filling a single display. When using multiscreen, it
depends on the windowmanager if and how you can move windows
between displays, but then you can also configure correct maximizing
behaviour. At last, that the theory - i never did extensive tests with
multiscreen, because i prefere xinerama. The only setup where
mutliscreen might be prefered is IMHO when you like to run seperate
full screen applications in parallel (i.e. video-playback during a trade
show).

BTW.: concerning the naming convention:
"xinerama-twinview-twinview" means: LCD1+LCD2 and LCD3+LCD4
are configured in twinview mode and then combined with xinerama.
It would also be possible to have something like
"multiscreen-twinview+dualview" where LCD1+LCD2 make one
screen (:0.0) in twinview mode and LCD3 and LCD4 are keept as
screens :0.1 and :0.2. However, i currently can't imaging an
application where such a setup could be usefull :-)

regards

Bernhard

[ballakilley]

These sample xorg.conf files were extremely useful. I had struggled for two days to get my system to work. I had got up the learning curve but was stuck at the final hurdle. I could only get any two of my three screens to work properly. Now it all works as I want.

My configuration from left to right is:

NEC LCD2090UXi 1600x1200 Rotated CCW i.e Portrait Attached to an Nvidia 7300LE DVI port

DELL 3007 2560x1600 Attached to an Nvidia 7300GT Dual Link DVI port

NEC LCD2090UXi 1600x1200 Rotated CCW i.e. Portrait Attached to an Nvidia 7300LE Vga port (Resolution might be a little bit better on a DVI port if I had a dual DVI card.)

I can open windows and move them to other the other monitors and maximize works at the monitor level. Thanks a lot for your sample xorg.conf files.