Success: Late '15 5K iMac + 2 4K displays @ 60 Hz

Discussion in 'iMac' started by Razorback7, Oct 13, 2015.

  1. Razorback7 macrumors newbie

    Joined:
    Jul 28, 2011
    #1
    I'm trying to determine if the new 5K iMac will drive two external 4K displays in 60 Hz mode. I think I read that it was supposed to, but haven't seen confirmation yet. (I apologize if I overlooked it!)

    Does anyone have a spec that will confirm this?

    Thanks.
     
  2. jcr918 macrumors regular

    Joined:
    Nov 8, 2012
    #2
    good question I would also like to know this I am debating on upgrading from a late 2013 iMac to 2015 5K iMac
     
  3. Razorback7 thread starter macrumors newbie

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    Jul 28, 2011
    #3
    Me too.

    My other thought is to purchase a Dell 5K display, use both Thunderbolt ports to drive it, then do a USB 3 third monitor at 1080p resolution. I would keep my Windows VMs/RDP sessions on that monitor. (Those don't do a good job of utilizing Retina resolutions anyway.) Has anyone tried that?
     
  4. dborod macrumors regular

    Joined:
    Jul 22, 2002
    #4
    I have submitted this question and have a call scheduled with an Apple genius tomorrow afternoon about this specific question. I'll respond here with whatever I discover.
     
  5. adgoodma macrumors newbie

    adgoodma

    Joined:
    Apr 29, 2015
    Location:
    Boulder
    #5
    This seems to be the million dollar question that everyone is asking on these boards...
    How well does a 395x chip run 2 4k screens? But also, how does the 380 chip or the 390 chip run these screens.. what the heck is the practical difference?
     
  6. Razorback7 thread starter macrumors newbie

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    Jul 28, 2011
    #6
    Did you hear back from the genius?
     
  7. whodatrr macrumors 6502a

    whodatrr

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    Jan 12, 2004
  8. Sirmausalot macrumors 6502a

    Sirmausalot

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    Sep 1, 2007
    #8
    does an extra screen draw significent rsources away from the gpu?
     
  9. dborod macrumors regular

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    Jul 22, 2002
    #9
    They did not have any details beyond what's on Apple's web site. They said they would keep looking and get back to me.
     
  10. jcr918 macrumors regular

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    Nov 8, 2012
    #10
    Yup Apple is clueless about this. Hopefully someone can answer this soon
     
  11. whodatrr macrumors 6502a

    whodatrr

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    Jan 12, 2004
    #11
    Apple says, in writing, that they support two external displays...

    Simultaneously supports full native resolution on the built-in display and up to two 4096-by-2160 external displays or one 5120-by-2880 dual-cable external display
    Found that tidbit here...
    https://support.apple.com/kb/SP731?locale=en_US
     
  12. Razorback7 thread starter macrumors newbie

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    Jul 28, 2011
    #12
    Boros, that is a great find! Let's hope that is accurate.
     
  13. dborod macrumors regular

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    Jul 22, 2002
    #13
    Yes, we know the 27" can drive two 4k external displays, but the question we all have is 'at what frequency?' One at 60Hz and one at 30Hz? Both at 60Hz? Both at 30Hz? Do the 4 different graphics options all have the same capabilities to drive the external displays?
     
  14. jcr918 macrumors regular

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    Nov 8, 2012
    #14

    Apple told me that the 5K iMac can only drive ONE external display at 4K 60HZ with the 5K resolution iMac screen and another at 4K 30HZ or two monitors at 2K 60HZ

    I am not sure how accurate this is they sort of didn't seem to sound like they new a lot. It will be nice when someone can chime in on this with a definite answer
     
  15. Razorback7 thread starter macrumors newbie

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    Jul 28, 2011
    #15
    Just received my Late 2015 5K iMac. I have verified that you CAN run two 4K displays at 60 Hz!
     
  16. dborod macrumors regular

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    Jul 22, 2002
    #16
    Which graphics card option does your Mac have?
     
  17. Razorback7 thread starter macrumors newbie

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    Jul 28, 2011
    #17
    395X. Here's a screen shot of the System Report. (Yes I know the Dell is a 5K monitor... it was the most convenient for testing.)

    [​IMG]
     
  18. whodatrr macrumors 6502a

    whodatrr

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    Jan 12, 2004
  19. BarryBettell macrumors newbie

    BarryBettell

    Joined:
    Dec 22, 2015
    #19
    Hey! Thanks for this post! I am purchasing my late 2015 5k iMac in a few days and ill also be ordering 2 Asus PB287Q 4k displays! The iMac i will be ordering will have the M390 inside so i will reply here with the results if it can run the internal 5k display + two 4k displays at 60Hz etc!
     
  20. makrom macrumors regular

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    Nov 4, 2015
    #20
    Any news on that? I'm thinking about buying 2 4k displays, but if only one would run properly on my M395, I might just get a 5k instead.
     
  21. BarryBettell macrumors newbie

    BarryBettell

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    Dec 22, 2015
    #21
    Hey! I ended up buying the mid spec 5k iMac with 2 Asus PB287q 4K displays and all 3 displays are running 4K 60hz the only issue I had was the iMac doesn't have a 4K display mode but to get around this all I had to do was install a program to change the resolution the program is called quickres. The reason I had to do this was because the iMac is a 'retina' it has preset scaled resolution but it works perfectly fine
     
  22. makrom macrumors regular

    Joined:
    Nov 4, 2015
    #22
    Thanks for your reply. That sounds like it shouldn't be a problem with the M395 either then.
    Now I still need to figure out whether I'm going for 24" or 27" screens, but that's another story. The UP3216Q with its 99.5% Adobe RGB coverage is also tempting, but I would prefer a smaller screen.
     
  23. ljonesj macrumors 6502a

    ljonesj

    Joined:
    Oct 20, 2009
    Location:
    Kingsport TN
    #23
    Display menu also lets u choose the 4k resolution
     

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