Dual External HDMI monitors (3840x1080)

Discussion in 'MacBook Pro' started by phillchannon, May 2, 2014.

  1. phillchannon macrumors newbie

    May 1, 2014
    Hey All,

    There seems to be quite a lot of conflicting information floating around (some here and other sites) about how exactly to connect a Macbook Pro up to 2 external monitors. So I'd like to get some definitive answers for myself and others that may be in this situation.

    My setup:
    - MBP 13" mid-2012
    - OS X 10.9.2
    - Intel Core i5
    - Intel HD Graphics 4000
    - 2 x ViewSonic 24" 1920x1080p monitors (identical)
    - Zotac MDP2HD dongle (mini display port to dual HDMI)

    Everything plugged in out of the box actually works ok, however my issue is with resolutions. Out of the box the external monitors get displayed at 2560 x 1024, which is a horribly stretched resolution and almost unusable.

    After doing a bit of reading, I understand that the MBP treats the 2 external displays as 1 single display, seeing as its only coming from 1 source, so I guess the only option is to experiment changing the resolution on the 2 externals to 3840x1080.

    I have tried SwitchResX and a few other tools to force the resolution change without any real success. I would assume I could force 3840x1080 using software and everything would simply work, as it seems to have for some people on here, except I get blank screens and nothing I try seems to work.

    I'm not even sure what I'm trying to achieve (3840x1080 across both monitors) is actually even possible, after checking the MBP tech specs on Apple's website it says the following:
    Although some people seem to have this setup working just fine, am I correct in assuming that the closest I can get on this MBP would be 2560x1080 or am I missing something obvious so that I can force the desired 3840x1080 ?

    And if so, how does the Matrox DualHead2Go adapters differ (their site says its compatible for my MBP) ? Do they have a separate GFX card built into the adapter that would upscale to 3840x1080 ?

    Thanks in advance!
  2. phillchannon thread starter macrumors newbie

    May 1, 2014

    Just to update this info.. after a fair amount of digging, I found this article.

    They seemed to achieve the desired result just fine, however when I do it as per the instructions, I get 2 blank screens - although SwitchResX and the MBP does seem to 'think' they are there/usable.

    The only thing I can think of is there may be some capability issue for the Intel HD 4000, as the 3000's seem to work ok ?
  3. HappyDude20 macrumors 68020


    Jul 13, 2008
    Los Angeles, Ca
    I always appreciate it when someone on these forums takes the time to post the solution even if they didn't have to.


    My only previous set up with a 2012 rMBP to an HDMI TV and thunderbolt to external monitor. After the new rMBPs are announced in the coming months I'm planning on doing a major redesign of my work space to include as many as 6 external monitors, especially considering Mavericks now supports a flawless screen changing implementation.
  4. phillchannon thread starter macrumors newbie

    May 1, 2014

    Thanks HappyDude, the initial idea was to grab bits and pieces of info about the subject from all over the place (which it seems to be at the moment) and post it here for a single point of reference for people - didn't quite work as expected :)

    That being said - Good news!
    I finally got the desired results with using both SwitchResX and OSXs display settings.

    After configuring SwitchResX as per my previous post, I still got the blank displays, although after going into System Preferences->Displays and playing with the OSX settings (which just displays the config that SwitchResX configured) I had to hit 'Gather Windows' to be able to see the settings for both monitors and then change the setting for the external monitors from 'Scaled - 3840x1080' to 'Best for display' and it automagically worked!

    So after a long winded search, it seems 50Hz was the key, and the rest was some finicky software modifications between SwitchResX and OSX.

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