GTX 980 HDMI limited bandwidth

Discussion in 'Mac Pro' started by slughead, Oct 1, 2016.

  1. slughead macrumors 68040

    slughead

    Joined:
    Apr 28, 2004
    #1
    Setup
    Mac Pro 5,1
    GTX 980 (not flashed)
    ROG SWIFT PG348Q
    OS X Sierra
    Latest Nvidia drivers

    The problem:
    When plugged into the Displayport on the monitor, everything works as expected, it goes up to the expected resolution of 3440x1440 and I think it goes up to the expected 100hz. However, if I plug the GTX980 into the HDMI port (I believe it's HDMI 1.4), it is limited to 1080p when it is supposed to be able to go to 3440x1440 @ 50hz. It not only does not show higher resolutions in Displays preference pane but also attempts to force the resolution have failed, as below

    What I've tried:
    - My PC laptop runs it at full res over HDMI
    - My Mac Laptop (macbook pro) runs at full res over HDMI
    - I used a displayport -> HDMI adapter rated at HDMI 1.4 as well as the built-in HDMI port (neither works)
    - Manually entering in the Resolution/pixel frequency/porches and such using SwitchResolutionX utility and info gathered from exporting the EDID output on the PC laptop (Oh yes, I went there)
    - Manually entering the EDID data into the OS plist on my monitor (which I believe is what SwitchResolutionX does anyway)
    - Resetting monitor settings to default
    - Holding "option" while clicking the "scaled" radio button in Displays panel

    Does anyone have any other ideas?
     
  2. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #2
    The Pixel Clock Patch is the only thing I can think of. It is supposed to patch in support for oddball 3440x1440 HDMI timings, which sounds exactly like your problem.
     

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