mickenglish

Q: Problem with multiple displays

I have added a second monitor to my iMac. The iMac seems to have difficulties recognising the second monitor when it comes out of power saving mode. Sometimes I have to restart the computer one or more times before the second screen starts to receive signal.

I am using a thunderbolt cable and the second monitor  is a BenQ GW2760HS

Any suggestions?

iMac (27-inch, Late 2013), Mac OS X (10.7.5)

Posted on Sep 27, 2016 2:47 PM

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Q: Problem with multiple displays

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  • by rkaufmann87,Apple recommended

    rkaufmann87 rkaufmann87 Sep 27, 2016 3:18 PM in response to mickenglish
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    Sep 27, 2016 3:18 PM in response to mickenglish

    Unless your external display is Thunderbolt equipped you likely have the wrong cable. Please use a Mini-Display adapter to (VGA, HDMI, etc..) into the Thunderbolt port on the computer and then connect the correct cable to it. Then follow the Apple's directions in Use multiple displays with your Mac - Apple Support

  • by mickenglish,Helpful

    mickenglish mickenglish Sep 30, 2016 4:30 PM in response to rkaufmann87
    Level 1 (11 points)
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    Sep 30, 2016 4:30 PM in response to rkaufmann87

    Thanks for the quick response. What is  Thunderbolt? I thought it was just a fancy name for a cable. I have tried 2 different mini display to HDMI cables, with the same result. Sometimes I can jog it into life by removing and reinserting one end or the other of the cable, and other timers a restart works, but there is nothing consistent. Do you think a mini display to VGA will fix it?

    Regards

    Mick

  • by rkaufmann87,Solvedanswer

    rkaufmann87 rkaufmann87 Sep 27, 2016 3:44 PM in response to mickenglish
    Level 9 (58,914 points)
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    Sep 27, 2016 3:44 PM in response to mickenglish

    Thunderbolt is explained in http://www.apple.com/thunderbolt/.

     

    You need an adapter cable similar to one of the ones on the following web page:

     

    http://www.apple.com/us/search/Mini+DisplayPort+Adapter?src=globalnav

     

    Please note that not all adapters are created alike, if you buy a cheap one then expect it to give you problems. If you buy a quality one then it should be okay. Once you have the connection made then please follow the advice letter in my initial post.

  • by mickenglish,Apple recommended

    mickenglish mickenglish Sep 30, 2016 4:40 PM in response to rkaufmann87
    Level 1 (11 points)
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    Sep 30, 2016 4:40 PM in response to rkaufmann87

    Thanks again, I bought another mini display to HDMI cable but the problem persisted. Using the links you provided, I tried the SMC reset, which I thought had fixed it but next day - same thing. Then I tried resetting NVRAM..hooray! (well-so far) If it goes OK for a few more days I will consider the problem licked. Thanks for your input.

  • by rkaufmann87,

    rkaufmann87 rkaufmann87 Sep 30, 2016 4:46 PM in response to mickenglish
    Level 9 (58,914 points)
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    Sep 30, 2016 4:46 PM in response to mickenglish

    I Will keep my fingers crossed.

  • by mickenglish,Helpful

    mickenglish mickenglish Oct 7, 2016 4:33 PM in response to rkaufmann87
    Level 1 (11 points)
    Desktops
    Oct 7, 2016 4:33 PM in response to rkaufmann87

    Sadly the problem still exists. I can get the second monitor working by shutting down and unplugging  the computer  and then doing  a restart. Occasionally a simple restart will fix it  but once the computer has  gone into power saving (sleep) mode, it  ceases to recognise the second monitor until I do one or the other.

    I'll try a new mini display to HDMI  adapter just to fully eliminate that possibility.

    Regards

  • by mickenglish,

    mickenglish mickenglish Oct 7, 2016 4:37 PM in response to mickenglish
    Level 1 (11 points)
    Desktops
    Oct 7, 2016 4:37 PM in response to mickenglish

    Success! A new (third) mini display connector seems to have resolved  the problem. I thing the best approach to this would be  (1) Reset SMC (2) reset NVRAM, and if that doesn't fix it, try another connector. Happiness has descended upon my workstation.

  • by rkaufmann87,

    rkaufmann87 rkaufmann87 Oct 7, 2016 11:31 PM in response to mickenglish
    Level 9 (58,914 points)
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    Oct 7, 2016 11:31 PM in response to mickenglish

    Your welcome.

  • by mickenglish,

    mickenglish mickenglish Oct 8, 2016 3:15 PM in response to rkaufmann87
    Level 1 (11 points)
    Desktops
    Oct 8, 2016 3:15 PM in response to rkaufmann87

    Apologies, I thought I had acknowledged you in a previous response. Thank you again for your advice which turned out to be entirely correct.