MacPro 3.1 / 980 Ti - 4k image shrunk (switchresx?) No screen in recovery mode

Discussion in 'Mac Pro' started by thestudentisrea, May 23, 2018.

  1. thestudentisrea macrumors newbie

    Jun 23, 2009
    Just got a Geforce 980 Ti and 4k tv for my old (not Hack) MacPro 2008. 4k image is too small, and no controls for scaling, so trying to use SwitchResX, but it now says no custom anything in OSX 10.11.6 (can't update further) without first disabling SIP which seems to require CMD R at boot. Unfortunately, no screen comes up when I do this.

    Is this because the 980Ti can't display the recovery mode boot screen? It is "mac flashed", and does display option boot for drive selection. Is something else going on, or am I going to need to reinstall the factory card just to access recovery mode just to disable SIP? If so, can I just keep both in there? Does it matter that the 980Ti is occupying the bottom 2 spots?

    Am I missing another utility or simpler way I can get scaling options or other way to fix the display?

    Ultimately trying to output 4k 60hz 4:4:4, but so far no part of that is working properly (also only have 30 hz or 24 hz options. Anyone got a step by step on how they got 4k 60 hz 4:4:4 from a mac with 980ti (either by HDMI or DP to HDMI)
  2. AlexMaximus macrumors 6502a


    Aug 15, 2006
    A400M Base

    I am not entirely certain, but make sure you use the original display port and if needed the mini Display adapter.
    The HDMI ports seems to be kind of TV ports and not really full Computer resolution ports. Can you elaborate on the needed 4:4:4 resolution you need to have?
    I also would check the settings and capabilities on your 4K TV. I somehow have the gut feeling there is something screwy with your TV. HDMI is not always digital, many TV brands jumped on the 4K bandwagon with models that have been retrofittet with a 4K capabilities and (low budget HDMI ports, but not with the full res. power) in the last minute, however with hefty "kind-of & somewhat" solutions.
    HDMI ports have different standards. Display ports have differnt standards. 4K is "stretchy & skiddish" as well.

    Check your capabilities / requirements of that 4K TV and read the small print. See if you can find info about the Display Frimware and Display 1.2 or 1.3 or 1.4 port standard. Maybe you need a different cable?
    Out of my experience the 980Ti is a superior GPU. The way you describe your problem, it sounds like a TV port & port support problem. There might be also a software solution to get it right, but that is usually not a good solution, your resolution setting should be set in the driver software associated with the firmware and the correct port.
    Sometimes not every HDMI port is really the same, - its like a USB3 pcie card with four ports but sharing only one controller... the chinees elchepo's are always dangerous in that extent..
    This problem is a bit out of my leage, hope I could help you at least a little bit for pinning down the exact problem..
    Good luck hunting it down!
  3. thestudentisrea thread starter macrumors newbie

    Jun 23, 2009
    The TV is a brand new TCL 65S405. confirmed that they got it to display 4k 60hz 4:4:4, though they didn't specify how except to say it needed to be PC input. There are only 3 HDMI2.0 inputs, no other input type, so whatever they did, it came into the tv via HDMI. New cable (and dv/hdmi active adapter) ordered but not yet delivered. The 4:4:4 is for video editing / photoshop.

    When you say "be sure to use the original display port if needed" are you referring to the stock card? It's not in the tower any more. That's the basic question: Do I need to reinstall the stock card in order to see the boot screen in recovery mode? If so, can I just leave it installed, and does the pcie slot order matter since the 980Ti is currently covering the bottom 2 slots. If I can just leave both, how is that managed? Does it boot off the original first so full recovery mode, etc... but then I switch it somehow to Nvidia card manually once it's running?
  4. thestudentisrea thread starter macrumors newbie

    Jun 23, 2009
    Worked like a charm, thx... though I may not need SwitchResX now. Right after disabling SIP, my new high speed HDMI cable arrived. Swapping that did nothing, but my new active DP to HDMI adapter came too, and when I come out of the DP port on the 980 TI into the adapter, 4k 60 hz shows up as the default option in System Prefs... and it's sized correctly.

    It appears that the issue is some sort of limitation on the (supposedly) HDMI 2.0 output of the 980Ti. No matter. It's got 3 DP outputs, and I only actually need one.

    Just need to figure out now how to output rec709 gamut in 8 bit at 4:4:4 as none of the color choices seem to be indicating the 4:4:4 part.
  5. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    There is no native HDMI 2.0 support in macOS. Becasue there is no Mac has HDMI 2.0 output, Apple no need to support that.
  6. thestudentisrea thread starter macrumors newbie

    Jun 23, 2009
    Gotcha. I assumed that installing the Nvidia drivers would clear those sorts of issues up. All I know for sure is that the options that would require 2.0 didn't show up in SwitchResX either until I did the DP/HDMI 2.0 conversion. It's all good, though. A $25 converter, and I'm good to go with 2 more DP ports to spare.

    Thx again.
  7. orph macrumors 68000


    Dec 12, 2005
    you may need to look in to something like this or
    not relay shore tho, dont know anything about TV's

    have you used a calibrator to calibrate the display?

    the review is a tad confusing, it lists the tv as DCI P3 81% so i gess it's close to rec709 but without calibration your blind to it if you want it to be close to rec709

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