LinuxQuestions.org - Debian Lenny + Nvidia Quadro FX 380 LP -> black screen on iMac 27"

My problem is as follows :

I'm using a desktop PC (I will call it "PC" in this post) with a Debian Lenny distro with kernel 2.6.26-2-686.

I want to use my new Apple iMac 27" as an external screen for that Linux OS (I will call it "iMac screen" in this post).

In order to use the iMac screen as an external screen for the PC I needed a graphics card with a Displayport, that's why I bought a Nvidia Quadro FX 380 LP.

The motherboard of the PC has an onboard graphics card, too. Up until now I used an Acer screen connected via VGA to the motherboard's VGA connector.

I installed the Nvidia driver with the Nvidia pkg (not the Debian way), as it is a recent card. I followed the description of the following site (section A, sorry, it's in French) :

http://www.commentcamarche.net/faq/s...drivers-nvidia

I used the recommended driver for a Linux 32 bit system (190.53).

The installation was successful and when I rebooted the PC after installation the Nvidia graphic card's fan went from full speed to something much slower (normal speed). The usual beep indicating the introduction of the username/password indicated that X is charging normally. I could not check this visually as I had to change the BIOS in order to use the PCI graphics card, the Acer screen was black, which is normal (I don't think I can use both graphics card in the same time).

Then, when I connected the iMac screen via the Minidisplayport - Displayportcable (from circuitassembly.com) to the Nvidia FX 380, the iMac Screen remained black and after maybe 10 seconds switched back to the OSX content (the switching can be toggeled via "Cmd+F2" between OSX and target mode for use as an external screen).

I thought that the problem must be in the xorg.conf file. So I tried different solutions, but none was the good one. The iMac screen remains black.

To be sure that the connection between the PC and the iMac screen works, I installed Windows XP on the PC and installed the Windows Nvidia driver for the graphics card. The iMac screen shows the Windows XP content and serves as an external screen without any problem.

Does anybody have an idea where the problem could be ?

Here is the lspci output :

00:00.0 Host bridge: Intel Corporation 82G33/G31/P35/P31 Express DRAM Controller (rev 10)
00:01.0 PCI bridge: Intel Corporation 82G33/G31/P35/P31 Express PCI Express Root Port (rev 10)
00:02.0 VGA compatible controller: Intel Corporation 82G33/G31 Express Integrated Graphics Controller (rev 10)
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 01)
00:1c.0 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 1 (rev 01)
00:1c.1 PCI bridge: Intel Corporation 82801G (ICH7 Family) PCI Express Port 2 (rev 01)
00:1d.0 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #1 (rev 01)
00:1d.1 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #2 (rev 01)
00:1d.2 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #3 (rev 01)
00:1d.3 USB Controller: Intel Corporation 82801G (ICH7 Family) USB UHCI Controller #4 (rev 01)
00:1d.7 USB Controller: Intel Corporation 82801G (ICH7 Family) USB2 EHCI Controller (rev 01)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev e1)
00:1f.0 ISA bridge: Intel Corporation 82801GB/GR (ICH7 Family) LPC Interface Bridge (rev 01)
00:1f.2 IDE interface: Intel Corporation 82801GB/GR/GH (ICH7 Family) SATA IDE Controller (rev 01)
00:1f.3 SMBus: Intel Corporation 82801G (ICH7 Family) SMBus Controller (rev 01)
01:00.0 VGA compatible controller: nVidia Corporation Device 0a78 (rev a2)
01:00.1 Audio device: nVidia Corporation Device 0be3 (rev a1)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02)

The Nvidia card doesn't seem to be mentionned. I think this is related to the fact that I had to change the BIOS to use the internal graphics as primary one, in order to use the Asus screen via VGA.