cMP + Sierra + GTX 1080 + HP Z27q = no 5k ?

Discussion in 'Mac Pro' started by ArleX, Jul 5, 2017.

  1. ArleX macrumors newbie

    Joined:
    Jul 5, 2017
    #1
    Hi, I've been trying to move from my old Dell 30" monitor and jump on the HiDPI bandwagon but had no luck in the process.

    My detailed setup is the following:
    • cMP 4,1 flashed to 5,1
    • MVC flashed GTX 1080 (evga ACX 3.0), with 2 DP, 2 mini DP and 1 DVI
    • Latest Sierra (10.12.5)
    • Brand new HP Z27q monitor, that should support MST to reach 5K over dual DP, linked using supplied DP cables to the 2 DP ports of the GTX1080.

    My intial action was to disable SIP and set the nvram parameters to enable MST in nvidia driver as indicated elsewhere ("boot-args=kext-dev-mode=1 nv_spanmodepolicy=1").

    Z27 display is properly setup for Display Port 1.2 (no other option on the OSD to explicitely enable MST).

    I understood that fumbling with display overrides files was not necessary under Sierra as it contains the definition for the HP display.

    I never got this setup to work in 5k, even if I think I tried all the full size DP-links order and power-on sequence combinations. I always see two HP Z27 displays appearing unders the Display pane of system Preferences. The second one being with an odd 2560 x 2880 resolution but not displayed on the physical screen.

    At one time I selected the mirror mode, "Optimize for the second display" in the pull down menu, and got a 5k image on screen but with 2 duplicated Desktops and an instable image travelling across the screen. Since that time, I have a flickering of the display and some persistence of my Desktop behind the OSD for example, even after a very long power cycle of the screen (several hours). I can't even find a way to get back to a clean 4K mode.

    Did any of you found a way to get 5K on a cMP with a GTX 1080 ? Should I try to use the other miniDP instead of the DP ? Any other ideas on how to get it working ?

    Thanks
     
  2. Squuiid macrumors 65816

    Squuiid

    Joined:
    Oct 31, 2006
    #2
    My guess is that an RX 580 is more likely to support MST correctly in macOS given it's use in the latest 27" 5K iMacs.
    I know, not that helpful but it may be your only route.
     
  3. mattspace macrumors 6502a

    mattspace

    Joined:
    Jun 5, 2013
    Location:
    Australia
    #3
    it will be interesting to see if MST5k works with eGPU on an RX580.
     
  4. Fl0r!an macrumors 6502a

    Joined:
    Aug 14, 2007
    #4
    From my personal observations I'd guess that Nvidia GPUs only support 5K when using the Dell UP2715K.
     
  5. ArleX thread starter macrumors newbie

    Joined:
    Jul 5, 2017
    #5
    Thank you all for the answers.

    I installed Bootcamp (which was a little bit painful) and booted in Windows 8. Once Nvidia Drivers and HP display drivers were installed in Windows, the display worked without any issue in 5K and without fumbling with the cables. So I guess the issue is not the GTX 1080 hardware itself.

    But still not working when rebooting under MacOS. Since the Z27q is supported by Apple, I guess the only remaining issue is in the Nvidia drivers. I'll try to report that bug to NVidia to see if a correction can be expected in the future...

    Once in MacOs after the Windows experiment, I chose mirroring between the 2 instances of the display, and Optimise for the second one (the one not showed). The display is almost stable (much more than during my first attempt), with 2 partial duplicate desktops of 2560x2880 and a full one : IMG_8335.jpg

    The screen OSD correctly reports the right 5K@60Hz resolution. but there is a strange ghosting effect..
    Maybe I could achieve something using SwitchResX?

    The horrible flickering effect came back when unplugging the second DP cable. I guess it will be reset once I boot in Windows...
     
  6. Fl0r!an macrumors 6502a

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    Aug 14, 2007
    #6
    Yes, I wasn't precise enough. I wasn't talking about the hardware, but about macOS drivers.
     
  7. Squuiid macrumors 65816

    Squuiid

    Joined:
    Oct 31, 2006
    #7
    If you can, try and get your hands on an RX580, or even an RX560, as that is far more likely to work for you. Just ensure you're using 10.12.6 or High Sierra.
     
  8. carpsafari Suspended

    carpsafari

    Joined:
    Sep 13, 2015
    Location:
    the Netherlands
    #8
    Most likely you have to use a little work around as your MP will not boot in 5K. (like the Dell)
    You should be able to boot in 4K and than manually set it to 5K.
    My friend couldn't get it to work under Sierra, he uses EC.
     
  9. William Payne macrumors 6502a

    Joined:
    Jan 10, 2017
    Location:
    Wanganui, New Zealand.
    #9
    I'm a little out of the loop here, why would the Dell 5k Monitor work fine but the HP not work?
     
  10. carpsafari, Jul 10, 2017
    Last edited: Jul 10, 2017

    carpsafari Suspended

    carpsafari

    Joined:
    Sep 13, 2015
    Location:
    the Netherlands
    #10
    I don't think you got it!
    The Dell isn't working 'fine'!!

    You need this workaround to get 5K, knowing this, I urge you (the TS) to try the same workaround with the HP.
    I don't know of anybody using this HP.
     
  11. William Payne macrumors 6502a

    Joined:
    Jan 10, 2017
    Location:
    Wanganui, New Zealand.
    #11
    Sorry if that reply was for me I am not the original poster. I'm new to this thread, I'm not using any 5k monitors I was just asking out of curiosity.
     
  12. Synchro3 macrumors 68000

    Synchro3

    Joined:
    Jan 12, 2014
    #12
    Just wait for a 5K monitor with DisplayPort 1.4. One cable, one connector, no problems.
     
  13. mattspace macrumors 6502a

    mattspace

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    Jun 5, 2013
    Location:
    Australia
    #13
    Assuming such a thing ever happens. :/
     
  14. William Payne macrumors 6502a

    Joined:
    Jan 10, 2017
    Location:
    Wanganui, New Zealand.
    #14
    Excuse my ignorance but what would happen if you plugged a 5k monitor into one display port 1.4 socket?

    The pascal quadros claim to be able to run 4x 5k monitors at once?

    Is it a software limitation?
     
  15. mattspace macrumors 6502a

    mattspace

    Joined:
    Jun 5, 2013
    Location:
    Australia
    #15
    the 5k displayport screens around at the moment are all DP1.2 afaik, so they show interpolated 4k full screen with a single cable.
     
  16. Fl0r!an macrumors 6502a

    Joined:
    Aug 14, 2007
    #16
    There are some threads on this topic at tmx86. I don't think anyone managed to get the HP 5K working with a Nvidia GPU in macOS using the same methods which work for the Dell 5K.
     
  17. Squuiid macrumors 65816

    Squuiid

    Joined:
    Oct 31, 2006
    #17
  18. ArleX thread starter macrumors newbie

    Joined:
    Jul 5, 2017
    #18
    I would gladly try but since I have a Pascal GPU I am stuck in Sierra...

    I might try a used RX580 once they become available second hand and others have experimented.

    In the meantime, I just use it in 4K.
     

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