New iMac, thunderbolt ports not working as mini display?

Discussion in 'iMac' started by ri0ku, Jul 14, 2014.

  1. ri0ku macrumors 6502a

    Mar 11, 2009
    Hey guys, just got my new iMac 27" (had a 21.5" but apple messed up the repairs so I got an upgrade) I have a mini display port to HDMI adapter but when I plug this into the iMacs thunderbolt ports to have a 2nd monitor nothing happens... the adapter works fine in my surface pro.

    I am sure I used to connect this the same way with my old 21.5 2011 iMac and it worked. Am I missing something ?

    (Its just a cheap adapter from ebay) but it works on the Surface Pro..
  2. rkaufmann87 macrumors 68000


    Dec 17, 2009
    Folsom, CA
    Unfortunately not all adapters are created alike, I would recommend using another adapter. You can use the one Apple recommends from their store or another adapter, personally I have had good luck with and cables.

    Good luck.
  3. DeltaMac macrumors G3


    Jul 30, 2003
    Maybe it's the cheap adapter…
    If it did work on your older iMac, but was marginal, then you may need to replace with a different adapter. I would suggest that mini DisplayPort isn't your best choice, but should be ThunderBolt. The two connectors are very similar, but there's likely a reason that Apple points that out in a support article for Target Display mode.
  4. ri0ku thread starter macrumors 6502a

    Mar 11, 2009
    Thanks for the reply guys. I literally used to have my iMac 21.5 2011 model with a HP monitor connected as my 2nd display to extend the display with the same adapter. (Although now that I think it may have been a VGA adapter)

    Just seems strange that the cheap adapter works fine with another machine but not the iMac. I will try one of those monoprice ones you mentioned.
  5. scaredpoet macrumors 604


    Apr 6, 2007
    It's not *really* that strange. Different hardware will be stricter or laxer on certain standards compared to others. The windows laptop might not care if the cheap adapter is out of spec. Obviously Apple hardware has a known tendency to not be so blasé about these things.

    If you can borrow an Apple adapter from someone and see if that works, then you'll know for sure if the problem is with the adapter or the iMac.

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