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I am having troubles setting up dualhead with an NVidia Quadro FX3450/4000 card with Centos 6.2. The driver is installed from ELRepo.

I set up twinview with nvidia-settings (and checked /etc/X11/xorg.conf). Both monitors are recognized and properly set up (desktop spans both of them, for instance), but one of them always goes to powersave mode immediately.

Both LCD's are connected through DVI ports on the card and are functional (i.e. work with other computers, or when swapped).

My xorg.conf says:

Option         "TwinView" "1"
Option         "metamodes" "DFP-0: 1280x1024_60 +0+0, DFP-1: 1280x1024_60  1280+0;"

Here is a snippet from Xorg.0.log:

(**) Aug 03 13:45:50 NVIDIA(0): ConnectedMonitor string: "DFP-0, DFP-1"
(--) Aug 03 13:45:51 NVIDIA(0): Connected display device(s) on Quadro FX 3450/4000 SDI at
(--) Aug 03 13:45:51 NVIDIA(0):     PCI:1:0:0
(--) Aug 03 13:45:51 NVIDIA(0):     DELL 1908FP (DFP-0)
(--) Aug 03 13:45:51 NVIDIA(0):     AOC LM929 (DFP-1)
(--) Aug 03 13:45:51 NVIDIA(0): DELL 1908FP (DFP-0): 310.0 MHz maximum pixel clock
(--) Aug 03 13:45:51 NVIDIA(0): DELL 1908FP (DFP-0): Internal Dual Link TMDS
(--) Aug 03 13:45:51 NVIDIA(0): AOC LM929 (DFP-1): 155.0 MHz maximum pixel clock
(--) Aug 03 13:45:51 NVIDIA(0): AOC LM929 (DFP-1): Internal Single Link TMDS
(**) Aug 03 13:45:51 NVIDIA(0): TwinView enabled
(II) Aug 03 13:45:51 NVIDIA(0): Virtual screen size determined to be 2560 x 1024

Any hints to troubleshoot that?

I thought installing the nouveau driver would help (as it supports XRandr properly, and I would not miss 3D acceleration that much), but I cannot find it through yum. The system was installed by university staff and I am not sure which repository to enable to get nouveau.

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A colleague suggested that the power supply might be too weak, therefore the graphics card refuses to drive both DVIs... could that be the case? – eudoxos Aug 4 '11 at 12:33
up vote 1 down vote accepted

For technically unknown reasons, it was found (by accident) that both LCD's work if one of them is connected with VGA cable to its analog input, using DVI output of the graphics card with DVI-to-VGA adaptor. It also matters which DVI output is used with the DVI-to-VGA adaptor; if I swap DVI connectors, one of the panels will be blank again. Go figure.

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