El Capitan Won't Detect External Display

Discussion in 'OS X El Capitan (10.11)' started by jumapili, Jul 10, 2015.

  1. jumapili macrumors newbie

    jumapili

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    Jul 10, 2015
    #1
    I have 2 samsung monitors that worked fine before I installed the beta. Now I can't get the external display's to detect.

    Have tried to pram and smc several times.
     
  2. revokin macrumors member

    revokin

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    Oct 16, 2008
    #2
    I have 2 external displays on my 5k iMac. I can only get the iMac display and 1 external working. Can't get all 3 going at same time.
     
  3. jumapili thread starter macrumors newbie

    jumapili

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    Jul 10, 2015
    #3
    Are they the same type of monitor? Did the one work automatically? Or what did you do to get it working.
     
  4. revokin macrumors member

    revokin

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    Oct 16, 2008
    #4
    Both externals are the same type of display (Hanns-G HG281D). I didn't do anything to make them work, they just come up when I plug them in. Only issue is it only detects 1 of them, whichever I plug in first.
     
  5. jumapili thread starter macrumors newbie

    jumapili

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    Jul 10, 2015
    #5
    Interesting did you try the smc and pram? Did you click detect display in Display preferences? You know you have to hit opt for that button to come up right? I also have a 5k iMac. I have tried all of this to no avail.
     
  6. revokin macrumors member

    revokin

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    Oct 16, 2008
    #6
    Tried all of the above. Can only have 1 external display at a time. If I have all plugged in and unplug the current working display the other one pops right up.
     
  7. jumapili thread starter macrumors newbie

    jumapili

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    Jul 10, 2015
    #7
    Well you are doing better than I cause I can't get either to work :(
     
  8. keviig macrumors 6502

    Joined:
    Jun 7, 2012
    #8
    Same here. Can't get my external monitor to show up, even after trying all of the above.
     
  9. jumapili thread starter macrumors newbie

    jumapili

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    Jul 10, 2015
    #9
    So I am going to go purchase a new monitor just to see if it will work. If not back to the old os :(
     
  10. campyguy macrumors 68030

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    Mar 21, 2014
    Location:
    Portland / Seattle
    #10
    revokin, members in Apple's Dev Forums are reporting non-functional displays connecting via HDMI.

    I have two Dell P2715Q displays connected to my rMBP via mDP-to-DP cables - both work as expected and without issue at up to 4k @60Hz in either portrait or landscape mode or a combination of both with my internal display working perfectly, with no additional drivers or software installed. No lag.
     
  11. SandboxGeneral Moderator

    SandboxGeneral

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    #11
    FWIW, I'm using a Dell P2213 connected to my 2012 cMBP and its working fine for me. I'm using the mDP to DVI adapter to connect it.
     
  12. jggann, Jul 10, 2015
    Last edited: Jul 10, 2015

    jggann macrumors newbie

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    Oct 16, 2014
    #12
    I have two Dell monitors on a late 2013 MacPro. One is a 4k Dell P2715q and other is an older Dell U2711. After installing El Capitan, the 4k monitor will not work at all. The older U2711 works fine. I have tried the 4k as a single monitor, switched cables, initiated detect display, etc etc.....no luck.
     
  13. jggann macrumors newbie

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    Oct 16, 2014
    #13
    Adding to my above post, I am reinstalling Yosemite on the Mac Pro now and assume my P2715q will again work fine upon reversion to Yosemite. Meanwhile, also have El Cap installed on 2013 MacBook Pro. Noticing some wifi issues....lose connection, but then comes back. Whole system seems more sluggish than Yosemite....may revert MacBook back to Yosemite as well.
     
  14. jggann, Jul 10, 2015
    Last edited: Jul 11, 2015

    jggann macrumors newbie

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    Oct 16, 2014
    #14
    OK, my third post and I have a suggestion for people whose monitors aren't being detected. After much effort at trying everything from resetting PRAM (or whatever its called now) , Smc, changing cables, etc. I finally got both of my monitors working on El Capitan by merely unplugging the power cord to the monitor that was not working and plugging it back in a after a few seconds....not sure, but monitors must have something similar to resetting smc on MAC. Anyway, both of my monitors are working fine now and the 4k monitor shows the Apple startup which it did not do under Yosemite (this is a well known problem with Dell 4k monitor under Yosemite).
     
  15. jumapili thread starter macrumors newbie

    jumapili

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    Jul 10, 2015
    #15
    Okay So I went and got a Dell S2715H so it is HDMI instead of DVI on my 5K retina and when I left one of my Samsung 245bw's plugged in when I rebooted the both external monitors came up. So I shut down and put the Second samsung back on and booted nothing. Okay for me this problem is solved unless when I go out and get a second Dell S2715H two of them don't work.

    Btw this Dell 2514h looks great.

    Also... jggann that is called smc when you unplug...

    https://gigaom.com/2011/07/26/when-to-reset-your-macs-pram-and-smc/
     
  16. revokin macrumors member

    revokin

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    Oct 16, 2008
    #16
    I just hooked up both my monitors to my 2012 rMBP and they both came up fine. It's something with the 5k that doesn't play well with both of them. I've tried mDP->HDMI and mDP->DVI.
     
  17. revokin macrumors member

    revokin

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    Oct 16, 2008
    #17
    Anyone with issues try PB2 and have it fix it? I ended up going back to Yosemite but would go back to beta if display issues were resolved. Everything else worked great for me.
     
  18. Baastian macrumors newbie

    Joined:
    Oct 2, 2015
    #18
    Installed El Capitan this morning.
    And promptly my external display does not work.

    Also forcing to re-detect (hold the 'option' button pressed in the 'Displays' preferences screen), does not detect the screen anymore.

    I tried HDMI port, Thunderbolt -> DVI, makes no difference.

    Anybody else successfully got their external display working?
     
  19. hurley999jb macrumors newbie

    Joined:
    Jun 15, 2010
    Location:
    Los Angeles, CA
    #19
    I am connecting a mid 2013 Macbook Air to a ~2010 27" iMac via mini display port - I got it to work by unplugging the monitor and replugging it in, for whatever reason seems to reset it like others on this thread suggest.
     
  20. Tomasseee macrumors newbie

    Tomasseee

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    Oct 4, 2015
    #20
    It does not work for me, i unplugged, replugged, torned of and unplugged replugged the monitor, SMC,PRAM reset and so one, but does not work :( It works flawless under Yosemite
     
  21. h9826790 macrumors 604

    h9826790

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    Apr 3, 2014
    Location:
    Hong Kong
    #21
    I am on the other extreme, even my 4K TV is switched off, 10.11 still detect the TV and sometimes make my mouse disappear (the pointer move to the screen that is off).

    It is a bit annoying. Also, with that 4K TV detected, there will be a little bit lag in system UI when exit from mission control (enter mission control is normal).
     
  22. riceforlife macrumors newbie

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    Mar 25, 2004
    #22
    I'm having the same problem with a Dell monitor connected to an iMac 5K via mDP to DP. Would love to hear if anyone figures out!
     
  23. bug macrumors regular

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    Feb 2, 2004
    Location:
    Vancouver, BC
    #23
    Same problem for me - just upgraded and my Dell monitor is no longer detected.
     
  24. llirik macrumors member

    llirik

    Joined:
    Jul 24, 2011
    #24
    I am now having this issue as well on el capitan after upgrading from yosemite, on 2015 retina iMac. I even specifically waited for a .1 release of 10.11 to hopefully not have launch issues.
    On yosemite, it was working, but i had to turn off/on the monitor after ever restart/sleep, but it would work.
    now, nothing I've tried works.

    - thunderbolt to dvi = no joy
    - thunderbolt to hdmi = no joy
    - thunderbolt 2 dock, direct hdmi to hdmi = no joy
    - thunderbolt 2 dock, thunderbolt to hdmi = no joy
    - thunderbolt 2 dock, hdmi to dvi = no joy

    tried pram, smc reset. tried my old trick as well, no luck.

    interestingly, thunderbolt to hdmi on my 2015 retina mbp works. so does hdmi direct. same config on iMac as above does not.

    it's a dell monitor (2408wfp).
     
  25. quixani macrumors newbie

    Joined:
    Oct 27, 2015
    #25
    Wondering if anyone can help me. I have an early 2008 imac that I just updated to el capitan. I would revert back to the previous os except my time machine doesn't seem to be working (separate issue). So my problem is that I used to hook up to my very old tv but now it's not detected under display. I hold command and hit detect display. I have tried unplugging and re-plugging in the cable (hdmi?) but am unable to get my computer to mirror to my tv.
     

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