Triple-head with a 2nd (different) gfx card, possible?

[Thomas Cameron]

On 04/17/2012 08:23 PM, Wolfgang S. Rupprecht wrote:
>
> Fernando Cassia<fcassia at gmail.com>  writes:
>>     My current setup includes a PCI-X ATI X1600 board, which its dual
>>     DVI+VGA outputs.
>>     That card has two 19' monitors connected, a DVI one and a VGA-only one,
>>     both LGs.
>>     Now, suppose I don't want to buy another gfx board, but rather connect
>>     an external USB-to-VGA adapters like these:
>>     http://goo.gl/TqchG
>>     Would Fedora recognize the 3rd display (no matter it being much slower
>>     due to the USB 2.0 interface) and put the 3rd screen alongside the
>>     other two so I can move app windows from one monitor to the next?
>>     Or would it be a separate X display because it's handled by a different
>>     driver?
>
> It might well recognize the usb framebuffer (I have no idea if it will
> even do that.)  The stumbling block will be to get the current Xorg to
> span two framebuffers.  Back in the early days of X11 it did have an
> extension called Xinerama ( http://en.wikipedia.org/wiki/Xinerama ).
> That extension appears to have suffered bit-rot and no longer works for
> me.  I tried to get two different Radeon frame buffers to work together
> but ended up buying a new card that had at least three outputs.  Sadly
> those are hard to come by and they charge an arm and a leg.

I've been researching triple-head for quite a while, and the lest evil 
option I've come up with is the AMD FirePro 4900. It natively supports 
triple head from one card, has Linux drivers and config tools available 
from AMD, and is not horrifically expensive.

Have a look at 
http://www.amd.com/us/products/workstation/graphics/ati-firepro-3d/Pages/product-comparison.aspx 
for some comparisons of various video cards including how many monitors 
they support.

Hope this helps.
Thomas