Very confused about my iMacs 5k Resolution

Discussion in 'iMac' started by moosed, Mar 10, 2017.

  1. moosed macrumors newbie

    Joined:
    Mar 10, 2017
    #1
    So my 5k iMac screen got cracked, I ordered a new one to fit myself as the computer is out of warranty.

    I've attached it and its working but 5k resolution isn't available and when i click on the Displays setting in 'About this mac' it says that its 3840x2160.

    [​IMG]

    However when i go to resolution settings the max available one is 3360x1890 and that my default resolution looks like 1080p.

    [​IMG]

    However when i go to the system information screen it says its a 5k display...

    [​IMG]

    Anyone idea what could be going on ? Im bemused

    If anyone else here had a 5k iMac could you do me a favour and look at your display settings and see what your maximum scaled resolution is ?
     
  2. NT1440 macrumors G4

    NT1440

    Joined:
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    Location:
    Hartford, CT
    #2
    If you choose the "More space" option you'll get closer to the full 5K resolution.

    5K on Macs isn't to get 5K native resolution displayed (everything would be TINY). It's to mimic the standard resolutions available on that size screen but with a much sharper image.
     
  3. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #3
    Hi

    yes i realise 5k on a 27" would be ridiculously tiny but what I'm confused about is that when i select 'default for my display' it uses a resolution which 'looks like 1080p'... however i swear on my previous screen it used a higher looking resolution and i swear the max scaled resolution was 5120x2880.

    Or is my memory failing me ?
     
  4. NT1440 macrumors G4

    NT1440

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    May 18, 2008
    Location:
    Hartford, CT
    #4
    I've never owned a 27" so I can't comment on the max scaled resolutions, what happens when you select the option all the way to the right under "more space"? I imagine that's going to get you closer to what you're looking for.
     
  5. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #5
    Yes that obviously gives me a crazy small resolution which it says 'looks like 3360x1890'... its not so much that i want to run these crazy resolutions... i just want to make sure i've purchased the correct replacement screen !

    It would be great if someone else with a 5k iMac could confirm that this is the correct resolution for the maximum scaled value
     
  6. sartrekid macrumors 6502

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    Oct 30, 2014
    Location:
    Germany
    #6
    The max scaled resolution on the 5k iMac "looks like" 3200 x 1800.
     
  7. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #7
    See this is what is so confusing to me, mine is 3360x1890.

    Also when i click the 'default for display' button it switches to a res which 'looks like 1920x1080' but when i click the default button in the scaling it uses a resolution which 'looks like 3080x1692'

    utterly confusing, something is clearly muddled up.

    Does anyone know of any kind of process/driver reset i need to do when replacing a screen ? or should it just be plug and play ?
     
  8. theluggage macrumors 68030

    Joined:
    Jul 29, 2011
    #8
    I'd have thought "Default for display" on a 5k iMac should be "Looks like 2560x1440" (the old pre-5k resolution).

    3840x2160 is standard UHD as per so-called "4k" displays (which would default to "looks like 1080p").

    Sounds odd - you still need a 5k owner to confirm what a working 5k displays...
     
  9. sartrekid macrumors 6502

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    Oct 30, 2014
    Location:
    Germany
    #9
    I am a 5k owner and gave the data...
     
  10. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #10
    Yes, my previous screen defaulted to 2560x1440 when i clicked 'default for this display' but now when i do that it selects a resolution that 'looks like 1080p'

    The weirdest thing is that if i click the 'default' scaling tile in that screen it shows a resolution that 'looks like 3008x1692'

    I have the option to use 2560x1440 though... but its the middle scaling option and not listed as default. It looks correct though.

    So friggin confused. I don't understand how swapping out a screen could cause this ?

    It clearly says in the system information screen that the display is 5120x2880... so it must be the correct screen ?
     
  11. theluggage macrumors 68030

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    Jul 29, 2011
    #11
    You gave the max scaled resolution, but what's the "looks like" for "default for the display", and what does the "displays" tab say under the picture?
     
  12. sartrekid, Mar 10, 2017
    Last edited: Mar 10, 2017
  13. moosed thread starter macrumors newbie

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    Mar 10, 2017
  14. sartrekid macrumors 6502

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    Oct 30, 2014
    Location:
    Germany
    #15
    Here are the screenshots
     

    Attached Files:

  15. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #16
    Thank you.

    I take it the default middle one is 2560x1440 ?

    This is the same as what my previous screen was like. With this other one my resolution options are different.

    Im so confused. Thinking about reinstalling OSX and seeing if they go back to normal scaling options.
     
  16. NT1440 macrumors G4

    NT1440

    Joined:
    May 18, 2008
    Location:
    Hartford, CT
    #17
    Before doing so, it wouldn't hurt to do an NVRAM reset, it's quicker than a re-image. Probably won't solve it, but it's quick and worth the shot.
     
  17. Dustman macrumors 65816

    Dustman

    Joined:
    Apr 17, 2007
    #18
    Try resetting your PRAM and SMC.

    PRAM:

    Reboot whilst holding CMD+OPTN+R+P until you hear a chime a second time.

    SMC:

    Turn off Mac
    Unplug power cable
    Hold power button for 5+ seconds
    Plug in, and turn on
     
  18. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #19
    Thanks for the suggestions. I've tried both of those but no joy.
    --- Post Merged, Mar 10, 2017 ---
    Hi. I have one more request if thats ok ? could you go to 'about this mac', click on 'displays' and post a screenshot of that... or tell me what it says the resolution is.

    Cheers
     
  19. 960design macrumors 68020

    Joined:
    Apr 17, 2012
    Location:
    Destin, FL
    #20
    Here's what my 5K states:

    About This Mac > Displays > Built-in Retina Display 27-inch ( 5120 x 2880 )
     
  20. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #21
    Thanks. Hmm... I'm so confused right now.

    Why would mine show 3840x2160 but 5120x2880 in the system information screen.
     
  21. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #22
    Ok, did fresh install of OSX, same issue

    Sigh :(
     
  22. jerwin macrumors 65816

    Joined:
    Jun 13, 2015
    #23
    Screen Shot 46.png

    Hold down the option key while clicking on the "Scaled" radio button.

    I usually leave it at 2560x1440 but the native resolution is occasionally very useful for browsing digital archives*-- as well as certain older games.


    *for instance, the new yorker archives are legible as two page spreads-- if you boost the resolution, and have sufficient bandwidth.
     
  23. moosed thread starter macrumors newbie

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    Mar 10, 2017
    #24
    Hi. Thank you for taking the time to repond.

    I am aware of this shortcut however the issue is that my native resolution should be 2560x1440 but it is instead listed as 1920x1080. 2560x1440 is now a scaled resolution whereas on the previous screen it was the native resolution.

    Looking at your screenshot you do not even have 1920x1080 as a selectable resolution.

    It is as if the iMac thinks its a 3840x2160 monitor for some reason, but still lists it as 5120x2880 in the system information screen.

    It makes no sense whatsoever. I cannot find a single thing about this anywhere on the internet :(
    --- Post Merged, Mar 10, 2017 ---
    I think i've just sussed it out

    I found this in a listing for my display

    if your model is 5K Late 2015, it is 100% compatible with LM270QQ1 SDA2.
    if your model is 5K Mid 2015 or Late 2014, The maximum resolution is 4K.

    Doh ! and yet its listed as 5k in the system information. I guess for some bizarre reason it's not supported to display at that resolution
     
  24. jerwin macrumors 65816

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    Jun 13, 2015
    #25
    Ouch! Apple did have to design some custom circuitry (the "TCON") to get a 5K display before Display Port et al were ready. Perhaps the 2015 models have more of an industry standard design.
     

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