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I'm using a Lenovo x220i thinkpad, running crunchbang linux (which uses the openbox window manager). The laptop has a DP and VGA plug on the side.

Hooking up the DP and VGA cables and running xrandr, I notice that the following outputs are available/active:

LVDS1  <- the laptop screen

If I try to enable more that 2 (using any combination), then I get the error "cannot find crtc for output for [VGA1/DP1/LVDS1]"

What is crtc? How do I find out how many are available? Is it possible to add more in software or perhaps through a PCI card?


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crtc stands for cathode ray tube controller. In ancient times, monitors used to use a CRT rather than the LED display of today.

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+1 for knowing about the 'ancient times'. However, why would the mentioned error message appear if the crt IS actually connected? I'm only getting this message if I'm trying to activate a 3rd output. edit: whoops, I need 15 points to upvote :/ – neildaemond Sep 16 '13 at 16:42

I'm afaid that it's hardware limitation in your display device. I've simmilar situation - laptop(t430) with docking station. I can use in parallel 3 of monitors - 2*DP and LVDS or 3*DP or LVDS and DP and HDMI.. but enabling any monitor more show me the same error like yours.

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