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kalenpw
Asked: 2016-06-01 20:21:25 +0800 CST

Ubuntu detects 4th monitor, but doesn't detect the 4th monitor when plugged in

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Currently I am running ubuntu 14.04 and it works great with 3 monitors. When I plug in a 4th HP monitor that I have tested on a different computer I get an error could not switch the monitor configuration crtc 116 That is when I have all 4 monitors plugged into my R9 390, I've updated my drivers and rebooted still with the same thing. I followed the answer here ERROR : could not set the configuration for CRTC 64 and it still is not working. Currently what I've done is kept the 3 working monitors in my r9 390 and plugged the 4th into my 750ti and installed the proprietary nvidia drivers, but the monitor still isn't detected. If I go into displays and click detect monitors the 4th is never detected. Here is the output of lshw -c video

  *-display               
       description: VGA compatible controller
       product: Hawaii PRO [Radeon R9 290]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:01:00.0
       version: 80
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
       configuration: driver=fglrx_pci latency=0
       resources: irq:48 memory:e0000000-efffffff memory:f0000000-f07fffff ioport:e000(size=256) memory:f7200000-f723ffff memory:f7240000-f725ffff
  *-display UNCLAIMED
       description: VGA compatible controller
       product: GM107 [GeForce GTX 750 Ti]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:02:00.0
       version: a2
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller cap_list
       configuration: latency=0
       resources: memory:f6000000-f6ffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:d000(size=128) memory:f7000000-f707ffff

I've searched the display unclaimed message for the 750ti, but everything I see there is about uninstall the fglrx drivers which I didn't think would fix it, but I tried anyway and I'm still getting the same thing. How can I set it up so all 4 monitors are connected? I would prefer to have them all run off the r9 390, but if that is not an option I can use the 750ti all I really care is that all are dtected. Thanks.

Edit: I should add the monitor works in the BIOS and I can see the Error crtc 116 message on the 4th monitor so I know thought it's not a cabling issue.

14.04

1 Answers

  1. Best Answer

    I got this from reddit user /u/ProblyAThrowawayAcct, the issue was my HDMI -> DVI cable was passive which caused it took take 2x my cards output bus. Replacing that with a VGA -> VGA w/ DVI adapter cable resolved the issue.

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