Thunderbolt to DVI doesn't (always) work...

Discussion in 'MacBook Pro' started by kohsamui100, Jun 5, 2017.

  1. kohsamui100 macrumors member

    Joined:
    Dec 21, 2016
    #1
    For a long time I've been using this cable with really old Samsung Syncmaster 913B or a Haier monitor with my MBP 2011, converting Thunderbolth to DVI via an HDMI cable and a small DVI-D adapter, without any issue.

    Then I looked for a bigger screen, and when using the same cable on a Dell U2412M or a Samsung P2770HD, in both cases the monitors do not show any picture. The MBP screen would flicker when connected to the Dell, but will be steady and show the second monitor in preferences ("Syncmaster 27") when connected to the Samsung.

    I wonder what is wrong, and why it would work with they older monitors, but not with the newer/"better" ones....

    Any suggestion?
     

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  2. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #2
    Because thunderbolt is mini display port compliant not DVI and connects to display port on the new screens and the old DVI adaptor isn't compliant, just use a mini DP to HDMI cable for best results.
     
  3. kohsamui100 thread starter macrumors member

    Joined:
    Dec 21, 2016
    #3
    hmm..

    so in case the monitor has a displayport adapter, it's supposed to always work if I use a thunderbolt to display port cable ?

    what if the target monitor only has a DVI input ?

    why does it work when connected to old monitors DVi, but not to newer ones' DVI ?
     
  4. treekram macrumors 65816

    Joined:
    Nov 9, 2015
    Location:
    Honolulu HI
    #4
    First of all, it's important to make the distinction between Thunderbolt and Mini-Displayport. The 2011 MBP has a Mini-Displayport connector which can either send a Thunderbolt 1 or Displayport signal depending on the device that is connected to it. The first adapter you have, the one with the Mini-Displayport connector, is almost certainly not a Thunderbolt adapter. If you paid more than $50 for it, then maybe it is. The distinction is important as you look for the cable and/or adapter that will work.

    If you look on the web, you'll find that certain cables/adapters work in certain situations but not in others. I only see the Mini-Displayport connector in your picture and you mention DVI and HDMI so with that you have 3 possible points of problems - 2 conversions and the cable. I recently encountered a similar situation. I have a computer (non-Mac) which connected to an older Samsung monitor using and HDMI-DVI adapter with a dual-link DVI-D cable. That worked. But when I plugged it in to my 4-year old 2560x1440 monitor, it wouldn't work. That's just the nature of how these things work (or don't - in my case I'm guessing it was the HDMI-DVI adapter which was made before HDMI 2, which the computer has). Your best bet is to reduce the conversions that have to be done. In the case of Dell monitors, it appears they're notorious for having issues with Mini-Displayport to Displayport cables. If you look on the web, many people have issues with the P2770HD using HDMI. Hopefully somebody with your MBP and these monitors can give advice. Absent that, you just have to spend the time researching what other people have done to make it work. From this point on, you're going to have problems having your post being visible as it's likely that new MBP's will be announced and if they are, they'll probably be lots of posts on them.
     
  5. kohsamui100 thread starter macrumors member

    Joined:
    Dec 21, 2016
    #5
    Thanks for the detailed reply!

    As for the Samsung, it also has an HDMI input (which works), so no problem. The DELL was a screen I wanted to buy second hand, but considering it's being "notorious" in that manner, I might look for another option. I just like those DELLs with the rotating screen and height control... Should I just look for one which has HDMI input ?
     
  6. treekram macrumors 65816

    Joined:
    Nov 9, 2015
    Location:
    Honolulu HI
    #6
    For the Dell, if you like the monitor, do the following: 1) do the research (look for user reviews) and find out what works for other people; 2) find a retailer that has a good return policy; 3) be patient. I think you should be able to find a solution. I saw one person on one site who said that finding a good Mini-Displayport to Displayport adapter and then finding a Displayport cable was the easiest solution.
     

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