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Currently, failing to set up Xdmx correctly, I am trying to use 3 displays with 2 graphics cards in one machine under Fedora 15 and KDE. The 2 graphics cards are an ATI HD4670 (pcie) and (iirc) a Nvidia MX400 or similar (pci). The first card is driving a 1920x1080 + 1280x1024 display, and the pci one is driving a 1024x768 monitor.

The problem is that the output only goes over the HD4670, no matter what I do, and a lspci | grep VGA only shows the radeon card. It seems that the PCI card is being disabled by the BIOS, or something similar to that, as no output ever goes out of it during boot. I saw no BIOS options at all relating to video devices,

If anyone could find a solution to this, it would be much appreciated.

EDIT: Also, all the monitors, cables, and graphics cards are known-working, they've all been used with other systems.

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If a board does not show up in lspci, I'd suspect its not connected properly. Maybe you can try a different PCI slot.

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I guess that could be the issue, but the PCI slot works and it's the only PCI slot in the system. (It's a server board with 1 pcie and 1 pci). I'll try re-seating it and see if it fixes it. – Eli May 3 '11 at 1:09
Apparently the machine does now not show anything over the PCIe graphics card when I have the PCI one correctly seated. – Eli May 3 '11 at 14:30
Some BIOSes have an option to select the primary GFX adapter. – Turbo J May 3 '11 at 14:57
BTW: Some newer PCIe AMD cards can have more than 2 displays connected. That might be the simplest solution. – Turbo J May 3 '11 at 14:59
The motherboard happens to be a server motherboard, so I do not have any option in the BIOS to change the primary graphics display device. THe only thing similar to that is the jumper on the motherboard to enable the onboard graphics, but that disables pcie graphics. Also, I've tested my GPU and it only works with 2 monitors. – Eli May 4 '11 at 15:18

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