several cMP + Dell 5K questions

Discussion in 'Mac Pro' started by whwang, Nov 11, 2015.

  1. whwang macrumors regular

    Dec 18, 2009

    Just hook up a Dell 5K to my cMP (MP5,1, OS 10.10.5). My video card is GTX980(4GB) flashed by MacVidCard. I installed the nVidia web driver for 10.10.5. The monitor is connected with two DP cables that come with the monitor. Additional to the Dell 5K, I also have a Cinema display connected via DVI on the same video card.

    My first question is, the display system preference shows three displays instead of two. There is a tiny additional one, also marked as Dell 5K. Is that normal? How can I make it go away? Or I shouldn't?
    Screen Shot 2015-11-12 at 10.52.14 AM.jpg
    The second question is probably related to the first one. When I disconnect the ACD and turn on the computer, I can see the boot screen on the Dell 5K. However, the login console is not there. The display only shows blank desktop. With this, I can't login and not even shut down the computer. My guess is that the login console went to the small tiny display that doesn't physically exist. Is there any way to solve this? The ACD will be there for most of the time, but won't be always there. So I would like to make this Dell 5K standalone as much as possible.

    Also related, I can swap the two DP cables connected to the video card (when the ACD is not connected). If I do so, I will not have boot screen, but I will get the login console. This works better than having the boot screen but not the login console, but still not ideal.
    Screen Shot 2015-11-12 at 10.52.05 AM.jpg
    Then, for the Dell 5K, I find that I only have resolutions up to 3840x2160. Is there a way to enable the native 5K resolution? I know the text will be too small, but I really would like to try it and to would like to have such capability when I need it.

    Finally, if I use the 5K in 3840x2160 mode, the ACD sitting next to it does not have compatible window and text sizes. If I drag a window from the 5K to the ACD, it expands. Is there a way to shrink things in the ACD? Of I have to live with this?

    Thank you for any helps.

  2. scott.n macrumors 6502

    Dec 17, 2010
  3. whwang thread starter macrumors regular

    Dec 18, 2009
    Thanks. I did not find that when I googled around. Now I can enter the 5K mode. After the computer boots up, it enters the 4K mode + ACD by default. I power off the 5K and turn it back on, and then it enters the 5K mode. However, this kills the ACD. At this moment, I only have 5K or 4K+ACD. Is this the limit of the video card?
  4. HHarm macrumors regular

    Mar 4, 2009
    Getting the cMP (4.1->5.1) and UP2715K combo (and a MVC modded 980 Ti) to work still seems to require some extra steps. I got the display yesterday. Windows 10 worked right away in 5K but El Capitan showed two displays instead of one and sub 5k resolutions. When fiddling around I managed to lose the sync, get the hours worth of flicker that followed (and a headache). Finally the whole machine wouldn't boot - even into Windows.

    I the quickly reinstalled El Capitan. After the reinstall and some googling I ran sudo nvram boot-args="kext-dev-mode=1 nv_spanmodepolicy=1" in the Terminal. That activated 5180x2880 resolution (after turning the monitor off and on again). Hidpi mode wasn't still selectable so everything on the screen was very small. I then googled some more and copy pasted sudo defaults write /Library/Preferences/ DisplayResolutionEnabled -bool true into the terminal. Again I had to turn the display off and back on again to see the change.

    My question is this: Now that OSX is supposedly 5k compatible is it still normal that I have to turn the display off and on after booting to OSX? OSX always starts in lowdef 2560x1440 mode.

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