multi monitor/multi card status

Csillag Kristof csillag.kristof at
Sat Oct 10 16:15:54 PDT 2009

Dear all,

Please help me assess the general situation. I am trying to get a
multimonitor/multicard setup work with ati cards and the free radeon driver.

Here is my current understanting of how things go. Those with the proper
knowledge/authority, please confirm/correct/deny the following statements!

1. Monitors on the same GPU can be united into a big desktop using
randr. Unfortunately, most GPU-s can only drive at most 2 monitors.

    There are cards like the FireMV 2400, which have 4 outputs, but they
are internally two GPUs, so they do not count.

Q: are there any radeon cards with more than two digital outputs
connected to the same GPU?

2. To unite monitors connected to different GPUs (on he X server level),
one needs Xinerama.

3. Uniting a monitor from one GPU and an other monitor from an other GPU
works fine with Xinerama.

4. If one wants to use Xinerama to unite monitors from different GPUs,
and there is a GPUs which has more that one monitors connected to then,
it is not allowed to use randr to unite these monitors (before uniting
them with the rest, on the different GPUs), because randr and Xinerama
do not mix. Therefore, instead of the normal (randr) mode, one needs to
go with Zaphod-mode.

5. Zaphod more rarely gets any testing, and tends to be broken. (Right
now it seems to be.)

Q: If all the above is true, how the hell is one supposed to get more
than two monitors work? I would like to go triple-monitor, but I keep
running into obstacles.

Thank you for your help:


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