Hi, I've a problem.

I need a big desktop over 4 monitors, so I need two video cards for four video out.
Wich video card is better for have compositing active?

ATI DRIVER CLOSED
Can I manage two video card with fglrx and compositing active?

ATI DRIVER OPEN
xinerama support compositing over two videocards?

NVIDIA DRIVER CLOSED
With twinview I can manage two monitors but with two videocards what happens?

NVIDIA DRIVER OPEN
Too young (but with kubuntu 10.01 compositing work)

Any issue?

Bye

Hello,
actually I use two ATI Radeon HD video cards with four monitors.
I spent the last months investigating which video card/driver would be the better choice for a good desktop experience:

1. two nvidia cards with closed driver: A viable way to use four monitors. Anyway I wasn't able to activate desktop effects because of the mandatory xinerama mode. AFAIK xinerama inhibits compositing and windows movements are _very_ slow in redrawing.
2. two nvidia cards with nouveau driver: RandR compatible _but_ kwin isn't able to use each monitor as a display, with the consequence to have maximized windows across every two monitors. I tried some other window managers and I found out that only Icewm is able to maximize windows within each monitor.
3. two radeon HD cards with open radeon driver: same behavior as with nvidia cards.
4. two radeon HD cards with closed driver (fglrx): AFAIK this is the only usable and fast way to use four monitors with KDE desktop. RandR compatible, you can use rotation and different resolutions for each monitor. Compositing and Opengl work without problems. The only drawback is that I have to use two KDE sessions one for each card since KDE (Xorg?) is not able to drive multiple screens correctly.

My advice is to use fglrx driver with just one Radeon HD 5700 card which is able to drive three monitors without any problem. Keep in mind that the third monitor has to be DisplayPort aware: http://www.amd.com/us/Documents/ATI_Eyefinity_Technology_Brief.pdf

Hope it helps

It doesn't help me.
I need a configuration for 4 display with DVI input.

I've just tried an aty 5870 but the sapphire displayport-to-DVI adapter doesn't work for me so I can use only two display at the same time.

The main problem is that I've read that compositing doesn't work if xinerama is enabled ...

virgolus wrote:It doesn't help me.
I need a configuration for 4 display with DVI input.

I've just tried an aty 5870 but the sapphire displayport-to-DVI adapter doesn't work for me so I can use only two display at the same time.

The displayport-to-DVI adapter has to be an active adapter to let the graphics card manage three monitors at the same time. Passive ones are way more common and cheaper but useless for a third monitor to work.

virgolus wrote:The main problem is that I've read that compositing doesn't work if xinerama is enabled ...

As I stated before compositing do work for me with fglrx and three monitors hooked to the same card _without_ xorg xinerama extension. This is a snipset of my xorg.conf:

Code: Select all

Section "ServerFlags"
        Option      "Xinerama" "off"
EndSection


The fglrx in-driver xinerama extension doesn't inhibit compositing or DRI.