iMac 27" 2017 HDMI / DP Issue

Discussion in 'iMac' started by jmack007, Jun 11, 2017.

  1. jmack007 macrumors newbie

    Oct 18, 2016
    Not sure if this is the place, but maybe someone has an idea why this setup isn't working.

    I have a USB-C -> DP Cable and a USB-C -> HDMI 2 cable. When I use these cables on my 2017 Macbook Pro 15", they work great. 4k @ 60hz without an issue. However, when I use these same cables on my new iMac 2017 5k 27", nothing. The monitors (tried 3) are not detected and nothing flickers.

    Now, if I use an Apple USB-C Digitial AV Multiport cable on the same iMac, it works fine over HDMI, but ofcourse I can only get 4k @ 30hz which I cant stand.

    Any ideas why my these cables work on my MacBook but not on the iMac?
  2. jmack007 thread starter macrumors newbie

    Oct 18, 2016
    An update. I spent an hour with Apple and they couldn't figure it out either. Here are a few other things I have found out:

    1 - When I plug in the USB-C -> Display Port adapter into the iMac, nothing changes at all in System Report. If I plug it into the MacBook Pro, it shows as a USB 3 Billboard Device.

    2 - When I plug the USB-C -> HDMI (trendnet) adapter into the iMac, it does show in System Report, but as a USB2 device, when I plug it into the MacBook Pro, it shows as a USB3 device.

    Can someone with a 2017 iMac 5k please take a screenshot of the USB section of their system report and post it here?

    I am curious if there is an issue with the USB 3 bus, because I find it odd that there are only two bus' listed under the USB device tree, when the MacBook Pro shows three bus'.

  3. diabora macrumors newbie

    Jul 30, 2012
    --- Post Merged, Jun 15, 2017 ---
    Any news on this issue?

    Please chime in, if any of the lucky ones that has their 2017 iMac already, has been able to connect a secondary display via usb-c to HDMI adaptor.
  4. SCMedic macrumors regular

    Feb 8, 2008
    Just bought a USB-C to Displayport cable and my brand new iMac doesn't detect my Dell Ultrawide. WTF Apple. First the RAM problems and now the cable?
    --- Post Merged, Jun 15, 2017 ---
    Quick update, my USB-C port had an extra click that required a hard push to really seat. Fixed the problem for me.
  5. assoemitro macrumors newbie

    Jun 6, 2017
    Can anybody check both USB-C port? I remember somebody test that the left one is different from the right one when testing it as target display.
  6. Glockworkorange macrumors 65816


    Feb 10, 2015
    Chicago, Illinois
    Whoa, what are the RAM problems with the new iMac?

Share This Page