TripleDisplay issue Mac Pro 4.1, GTX660, GT120.

Discussion in 'Mac Pro' started by mortdawg, Aug 6, 2014.

  1. mortdawg macrumors newbie

    Jul 27, 2012
    Hi guys.

    I have a mac pro 4.1 with a GTX 660 and a stock GT 120.
    The 660 has 2 x DVI, 1x HDMI, 1x Displayport
    The GT 120 has 1x MiniDp 1x DVI.

    I have both NVIDIA drivers and stock drivers.

    I've recently received a Dell U3011 2560 x 1600 to compliment my 2 20 inch 1600 x 1200 monitors.

    I plan to have the 20's flank the u3011 in portrait on either side to create a PLP setup.

    The problem is that I can't get them all to work together.

    Most of the time the monitor on the left isn't recognised (in system information it is described as color LCD display) and displays a resolution of 480 x 640. The other two monitors will work fine.

    If I fiddle with the video outputs on 660 and 120 (mix them up, use adapters etc) I can get all three monitors to display their correct resolution, But if the computer sleeps or is restarted it goes back to low resolution on one monitor and doesn't display an image at all and goes to sleep.

    The U3011 is always recognised at its correct resolution via displayport.

    Other two are connected to DVI1 on the 660 and the DVI on GT120

    Currently both 20's are recognised as 'vga display' or 'color LCD', no resolution options are available, just what it defaults to (640 x 480)

    What it is at the moment:

    What it was before I had the 30 and was using a 24:

    I'm pretty sure its not a monitor issue, as the issues vary between monitors (depending on which is plugged in where)

    I'd prefer to resolve this issue by running everything off the 660, allowing me to remove the GT120.

    Any help would be much appreciated.

  2. mortdawg thread starter macrumors newbie

    Jul 27, 2012
  3. NOTNlCE macrumors 6502a


    Oct 11, 2013
    DMV Area
    Hi there, I run 3 x 1080p displays off my GTX 660 in my 3,1 no problem. I assume all the displays are connected via DVI? VGA displays have extreme issues under Mavericks, I've noticed. When I used to run a 1280x1024 display via VGA, I had to use the SwitchResX Preference Pane to run it at optimal resolution. If you are not running all the displays with a Digital signal (DVI, HDMI, or DisplayPort) I would recommend doing so if you are able. I know many older monitors only accept VGA.

    If they are VGA, please note that only one of the DVI ports on the GTX 660 broadcasts an analog video signal. If you are stuck using VGA, you will have to use the 120 and the 660 using VGA adapters on their respective DVI ports plus ofc a dual link DVI/HDMI/DP for your beautiful new main display. I recommend SwitchResX if you are in fact forced into VGA.
  4. MacVidCards Suspended

    Nov 17, 2008
    Hollywood, CA
    NOTNICE has some good leads there.

    VGA is an ancient thing that should be avoided if possible.

    May require purchasing DVI cables but worth it.

    Your 20" are not getting their EDID info to the video card.

    Also, Are you the one flipping their rotation?
  5. mortdawg, Aug 23, 2014
    Last edited: Aug 23, 2014

    mortdawg thread starter macrumors newbie

    Jul 27, 2012
    Sorry for the late replies.

    Both side monitors are using DVI. I've swapped DVI cables, doesn't change anything. Only adapter I am using is miniDP to DVI.

    Yep, won't touch VGA unless absolutely necessary.

    Yep, I manually set the rotation to 90 and 270 degrees respectively. The monitors seem to remember this configuration every boot.

    EDIT: I checked out SwitchResX, And it was able to force both side monitors to their native resolution. Thanks for the tip NOTNICE.


    Still, not too happy I'll have to pay for software to do something that OSX should do natively.

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