Running OSX Dual Monitor with iMac, PC Laptop, and VGA?

Discussion in 'iMac' started by Matty Quinn, Feb 7, 2014.

  1. Matty Quinn macrumors newbie

    Feb 12, 2013
    New Jersey, USA
    I recently bought a VGA cable and VGA to MiniDisplayPort adapter in hopes of running a dual monitor setup using my MSI Gaming PC Laptop (Somewhere from 2011-13) and my all-in-one iMac. I plug the adapter into my Mac's MiniDisplayPort and plug the Female VGA cable into the VGA end of the adapter, then plug the VGA cable into my laptop. The iMac seems to register that I have a VGA cable plugged in, as its screen turns to blue the way it should, however, it turns blue then goes back to a functioning screen for a few seconds. when I look at my PC, all that seems to have changed is the screen resolution. it's still running Windows 7, still functioning like a PC should, just not registering that I have it plugged in. In my Mac's display settings it shows I have two screens going, but the PC laptop doesn't show it. Help? I'm running OS X Lion 10.7.5, if that helps. Any recommendations would be lovely. Thanks advance, Matty.
  2. DeltaMac macrumors G3


    Jul 30, 2003
    I guess you are trying to use Target Display mode.
    Here's an article that should help you decide if you can do that with your computers. Older iMacs require Mini DisplayPort cables, and newer Macs would need thunderbolt cables - so - it depends on which iMac you have.
    And, you can connect to another Mac that has a MDP or Thunderbolt port.
    (it's not supported when booted to Windows, or on a Windows laptop)
  3. robgendreau macrumors 68040

    Jul 13, 2008
    VGA is a dumb, non-digital interface and your iMac is not gonna play display with that. There might be an active digital converter of some sort that would get it going, but good luck. The VGA adapter you have isn't really that; it's probably just a pass-through of an analog signal. TDM is sensitive to what's on the other end; it's not like a regular monitor setup.
  4. xraydoc macrumors demi-god


    Oct 9, 2005
    The adaptor the OP bought does not work in both directions. It's mDP to VGA only, not the other way around.

    The iMac's target display mode does not work with VGA signals. DisplayPort only on the 2010, Thunderbolt only on 2011+.

    Bottom line: the OP cannot do what he wants with his current setup.

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