Dual-display with Optiplex 7010 and CentOS 6.4



Hi, this is more a howto for those looking for a way to get their Dell Optiplex 7010 support dual monitor (or dual display) with CentOS 6.4. I had some issues at first and was about to give up but finally found a method and all is well, so I want to share.

My issues where:
1) of my two monitors, only one was active, even though I plugged each one to a DisplayPort connector.
2) the machine would lock when changing virtual terminals (CTRL-ALT-F1 to CTRL-ALT-F7).
Both issues are now resolved.

First of all, CentOS 6.4 puts the word "nomodeset" in the boot paramaters. You want to change that to "modeset" in the file /boot/grub/grub.conf. Once done, as root, run:
# grub-install --recheck /dev/sda

The option --recheck is important as without it, grub-install failed and produced the error message "no corresponding BIOS drive".

From now on, when you reboot, you will now see a much nicer boot screen, but more importantly, you can switch virtual terminals without locking the machine (issue #2 resolved).

The following step is done only once but must be done to recreate a working xorg.conf with dual monitor setup
Restart the computer, and at the grub screen, press any key before the timer runs out. Now scroll to the kernel line and add the word single at the end. Hit ESC and press b to resume the boot. Your computer will boot to single user mode (runlevel 1). Run the command
# X -configure

This will produce a xorg.conf.new file; make sure the new file uses the "modesetting" and "intel" drivers for Devices "Card0" and "Card1" respectively.

Rename and move it to the right spot:
# mv xorg.conf.new /etc/X11/xorg.conf

Reboot or change the runlevel with the command:
# telinit 5

You should have dual screens working now! (issue #1 resolved)

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Thank you very much for giving us a solution to an issue like this.

Sorry that no one noticed this sooner.

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