iMac Pro Dell UP2715K as a second screen on iMac Pro

Discussion in 'iMac' started by arepty, Apr 2, 2018.

  1. arepty macrumors newbie

    arepty

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    Nov 22, 2007
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    Bremen, Germany
    #1
    Hey,

    I’m thinking about getting an iMac Pro and I’m hoping that I can continue to use my Dell 2715K display as a second screen, but I cannot find a definitive answer on whether it’ll work. I asked Apple Support about it and they linked me to this: http://apple.co/1OygOoT

    I found this part in the article and asked them about it:

    “The Dell UP2715K 27-inch 5K display is supported by iMac (Retina 5K, 27-inch, Late 2014) and later and Mac Pro (Late 2013) running OS X Yosemite v10.10.3 and later.”

    Does that include the iMac Pro or does it mean only iMac (sans Pro) with a 5K Display are supported for this external monitor?

    They replied that it was a good question and that I should ask Dell about it. Why, I do not know. They have not reacted to any more follow-up questions. Dell have not gotten back to me yet.

    Does anyone have this exact setup? Does it work?
     
  2. jerwin macrumors 68020

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    #2
  3. arepty thread starter macrumors newbie

    arepty

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    #3
    I found that website, too, but it doesn't list the iMac Pro anywhere, it just lists the same configurations as the Apple resource that I linked to in the original post.

    So either nobody bothered updating their knowledge base articles when the iMac Pro came out (which is what I hope is happening here) or it simply won't work in 5K using two cables for multi-transport stream (MST). ¯\_(ツ)_/¯

    I was hoping that I would find at least one person who has attempted this before and can perhaps confirm or deny whether this works, but so far I have had no luck.
     
  4. arepty thread starter macrumors newbie

    arepty

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    #5
  5. Redneck1089 macrumors 65816

    Redneck1089

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    Jan 18, 2004
    #6
    Just be aware that the monitor will work fine unless it goes to sleep. Then you’ll actually have pull the power out of the back of the monitor to get it to work properly again. What I do to avoid this is turn the monitor off manually when I’m not using it or when I know I’ll be stepping away from the computer for awhile.

    The sonnet adapter works well for this display, as it frees up an extra USB c port on the iMac. I’m running my iMac Pro with both the Dell 5K and the old Apple 30” Cinema Display.
     
  6. arepty thread starter macrumors newbie

    arepty

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    #7
    I've actually noticed that while using this monitor before, even in 4K mode using mini-DP. I put one of those multiple socket extensions with a switch on my desk just for that.

    Ah, that's good to hear. Can you use the full 5160 x 2800 resolution at 60 Hz?
     
  7. Redneck1089 macrumors 65816

    Redneck1089

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    #8
    Yes, it should work at 60 Hz just fine.
     
  8. pam14160 macrumors newbie

    pam14160

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    Idaho
    #9
    I am using a Dell 2817 Q which is a 28 inch 4 G monitor with a 21.5 inch 2017 iMach, and it produces a really great screen, in all reality it is just as good if not better in some cases as the main screen on imac 21.5.
     
  9. arepty thread starter macrumors newbie

    arepty

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    #10
    I'm assuming that's just a single cable though, isn't it? The Dell UP2715K is problematic because in order to reach its full potential, it requires two cables from the computer to the screen and there have been a bunch of issues with that in the past. Some computers don't support it at all, which is why I was so nervous to buy a new iMac before verifying that it actually works.
     
  10. anticipate, Apr 4, 2018
    Last edited: Apr 4, 2018

    anticipate macrumors 6502

    anticipate

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    Dec 22, 2013
    #11
    I use the 2715K with my iMac Pro with no issues, at 5K/60 Hz, including usually* no issues with sleep. I use two Pluggable brand USB-C to DP cables. I have been running this since January.

    * Occasionally after sleep the screen comes up half-res, and I need to power cycle the screen. However that is relatively rare, and has not yet happened with MacOS 10.13.4.

    I didn't know about the Sonnet adapter, but it seems it will work. I may try it to free up another TB3 port.
     
  11. arepty thread starter macrumors newbie

    arepty

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    #12
    Good to hear of another case where this works mostly fine. I was freaking out a little bit that I might have to use the screen in 4K - which would look weird next to a 5K screen - but I guess it'll be fine after all.

    My iMac Pro should arrive tomorrow, along with my Sonnet adapter so I guess I'll find out then.
     
  12. anticipate macrumors 6502

    anticipate

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    #13
    c
    Great! I look look forward to hearing your experience too.
     
  13. arepty thread starter macrumors newbie

    arepty

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    #14
    Got the iMac Pro this morning and the Sonnet adapter later this afternoon, set it all up and it worked perfectly right out of the box. Even after the displays went to sleep, the Dell came up again just a few seconds later than the iMac Pro did.

    All in all, a great combo. Now I just need to get a tool to calibrate the displays properly because the white level is a tad off, but those are some hard-core first world problems.
     
  14. anticipate macrumors 6502

    anticipate

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    #15
    Awesome thanks!
     
  15. Redneck1089 macrumors 65816

    Redneck1089

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    #16

    Glad it is working well for you.

    Just as a note for calibration: Don't use DataColor Spyder for the Dell monitor. It won't work. You need to use XRite's iDisplay Pro. You'll be able to match both the iMac Pro's and Dell's monitor fairly closely with that.
     
  16. arepty thread starter macrumors newbie

    arepty

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    #17
    Thanks for the tip, I'll check that out once the difference starts really bothering me ;)
     
  17. arepty thread starter macrumors newbie

    arepty

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    #18
    After about half a week of iMac Pro usage, I've only had to cut the Dell's power one time because it wouldn't wake up from sleep. Usually it wakes up a few seconds after the iMac. All in all, I'm very happy with the combo.
     
  18. arepty thread starter macrumors newbie

    arepty

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    #19
    One more update for anyone reading this in the future and using the information here to decide on a purchase: now it seems that I'm having issues waking from sleep more often than not. Sometimes I get a black screen on the Dell, sometimes it's the right side of the screen stretched over the whole screen. The problems are always fixed by cycling power, so it's advisable to connect the monitor via a power strip with an extra button to avoid having to yank out the power cable every time.
     
  19. anticipate macrumors 6502

    anticipate

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    #20
    I have seen the stretch issue more than once - but I also saw that when I had toe USB-C to DP cables plugged in. It's a Dell issue I think. Other than that, the Sonnet box is working very well! Nice find. Good advice on a little power switch for the monitor. It is a pain to reset, although thankfully it happens very infrequently.
     
  20. ThatSandWyrm macrumors regular

    ThatSandWyrm

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    Indianapolis
    #21
    Yes, the Dell UP1715K will work. I've got two of them plugged into my iMac Pro right now. I'm typing this on one. I used to have one of them plugged into a late-2015 27" iMac.

    A few caveats though...

    1) If you have Thunderbolt 3, you'll need a TB3 to dual-DisplayPort adapter. I use ones from Sonnet. MAKE SURE that you get the one that's specifically advertised as being MacOS compatible. The PC versions are a little bit cheaper, but aren't certified with Apple as approved TB3/USB-C devices. The hardware is exactly the same, but Macs won't connect to uncertified TB3/USB-C devices.

    If your Mac has dual TB2 ports (like my old iMac did), then you'll just need Thunderbolt 2 to DisplayPort cables. My Dells came with these, but since you'll have to buy them used, you may not get them included.

    2) If you have an old version of MacOS, you may have to edit your PRAM variables to enable monitor spanning before 5K mode will work.

    3) Get a monitor resolution-switching app like "Display Menu" (it's in the App Store), since the Mac won't properly auto-detect the resolution of the monitor. By default it probably will not display in "Retina" mode, and all of your menus and text will be teeny-tiny until you enable retina-mode with Display Menu.

    4) If you're connecting multiple 5K monitors to an iMac Pro, make sure you use only even or odd USB-C ports. Like #1 and #3, or #2 and #4. That's because the first two, and last two USB-C ports use different "lanes" or something. One lane/controller/whatever can't handle the data load for two 5K monitors at once. This is why newer iMacs with 2 TB3/USB-C ports can't connect more than one 5K display.

    5) You'll have to fiddle a bit with the port connections, because the Dells are combining two different data streams into one 5K picture. One port carries a 4K signal, and the other carries the rest. Get them out of order and your monitor will show up as two different monitors with crazy stretched images.

    6) Set the color profiles for all of your monitors to "Adobe RGB (1998)" and they'll match way more closely than if you try and color-calibrate them yourself.

    7) Expect a few glitches. These Dells black-screen for 4-5 seconds whenever you change resolutions or switch inputs. One of my Dells does this every hour or so on its own while I'm working. Never happened on the 2015 iMac, and its frequency has gone down with every update, so I'm blaming MacOS on this one.

    Good luck. It sucks that these old out-of-production Dells look and operate much better than the LG 5K display Apple is selling. I have one of those too, for my laptop, and I hate it with a passion. Power button? Who needs a power button on a $1500 display? No, you're supposed to plug in your sleeping laptop for a charge, and then log in to be able to put it back to sleep (facepalm).
     

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