New iMac 27" with Dell U2711 2560x1440 as external (dual) monitor

Discussion in 'iMac' started by gnorknagar, Dec 16, 2012.

  1. gnorknagar macrumors newbie

    Dec 16, 2012

    I am planning on buying a new iMac 27". I currently have a PC with a Dell U2711 monitor running at 2560x1440. The monitor has DVI (2 DVI ports), HDMI, VGA and component. To be able to run 2560x1440 I am using the DVI port.

    I am wondering if I can connect this monitor to the new iMac 27", and run it as a second monitor (dual monitor, extended desktop).

    Is this possible? If so, what cable(s) do I need? Do I need the "Mini DisplayPort to Dual-Link DVI-adapter" because the external monitor is 27" and runs on 2560x1440? Or what cables do I need?

    Help is appreciated!
  2. M1sterd, Dec 16, 2012
    Last edited: Dec 16, 2012

    M1sterd macrumors newbie

    Aug 9, 2010

    I currently have a DELL U2711 which is connected to a Mac Mini via a display-port connection (i.e. my U2711 has a display port connector). I wonder if different revisions of the monitor have different connection ports?.

    [EDIT] If you click on the DELL monitors soft menu and then select Input Source roughly in the middle mine has an option for DisplayPort, does yours not have this?

    I was assuming that when I get my 27 inch 2012 iMac that I could connect it directly using the display-port.

    I would like to know if this is possible.

  3. iWaiting macrumors regular

    Dec 10, 2012
  4. bugbear99 macrumors member

    Mar 19, 2009
  5. iWaiting macrumors regular

    Dec 10, 2012
    only for a Apple monitor or another thunderbolt mac or I have been reading things wrong
  6. vooblu macrumors member

    Oct 23, 2012
    Did you want to use the monitor as a second display for the iMac, or did you want to use the iMac as a second display for your PC?

    The iMacs support output via mini displayport, which means you can use the Dell monitor as a second display for the iMac. This is listed on the iMac Spec's page:

    If you want to use the iMac as a second monitor for your PC, you need to have a PC motherboard with thunderbolt on it (and a thunderbolt cable is needed to connect the two). I have only seen one person confirm it works so far (since thunderbolt implementation on PC's is fairly new). From the spec's page:

    Someone feel free to correct me if I'm wrong, but I'm fairly confident that info is correct.
  7. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    M1sterd: I just noticed that I have a Display Port on the U2711 as well. I had not even noticed the physical port on the back of the monitor, but it is there. I can also select it in the monitors software menu.

    That might be good news, but as noted, the new iMac does not have a Display Port, it has two Thunderbolt ports instead. I also read that the Thunderbolt connectors and Display Port connectors are of the same format, but I do not know if it will work, and if so, how? What cable / adapter?

  8. iWaiting macrumors regular

    Dec 10, 2012
    same port physical format but a totally different beast electrically they are not interchangeable
  9. Imaginethe macrumors regular

    Feb 16, 2012
    If you are going to use the monitor as a second for your iMac, you need the Mini Display Port to DVI adaptor.

    If you want to use the iMac in Target Display Mode as a second monitor this will only work with other Thunderbolt enabled Macs. Your PC won't be able to use the iMac as a second monitor unfortunately.
  10. cosmicjoke macrumors 6502

    Oct 3, 2011
    Portland, OR
    the thunderbolt port absolutely works with a displayport monitor...

    a thunderbolt display, however, only functions with a thunderbolt port.

    i've used a U2711 w/ a mini displayport to displayport cable w/ my late 11's mbp's thunderbolt many a time... one thing to note is the first cheap cable i bought worked, but the screen wouldn't wake up after sleeping... i replaced it with a different cable which worked fine in such regards.

    anyways, hope that clears things up.
  11. Hexley macrumors 6502a

    Jun 10, 2009
    I will have the same physical setup. I will be attaching my 2012 27" iMac to my U2711.

    The cable I am using is the following.

    3ft 32AWG Mini DisplayPort to DisplayPort Cable - White for $4.12 (without shipping + handling)

  12. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    Thanks for all the replies.

    vooblu: Yes I only care about using the Dell monitor as a second monitor for the iMac.

    So, to sort things out the best I can.

    The Dell U2711 has a Display Port, the new iMac does not have a Display Port, but it has two Thunderbolt ports. The Thunderbolt ports have the same format as Display Ports(?).

    I will need a Display Port to Display Port cable? But what about Mini Display Port? umm?

    Can anyone point me in the right direction what cable I need, preferably with an URL directly to the actual cable :) Sorry, never had a Mac before, so Display Port and Thunderbolt are fairly new terms for me...
  13. theSeb macrumors 604


    Aug 10, 2010
    Poole, England

    You could use a Mini DP to Dual Link DVI adaptor or you could use a Mini DP to DP cable as mentioned above. The mini DP to DP cable is the cheaper option and you it allows you to leave both the PC and iMac plugged into the Dell monitor and then you can switch inputs in the monitor's menu.
  14. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    Hexley & theSeb: thanks!

    Hexley: I checked your reply and did some quick research and that cable seems to do the trick just fine!

    theSeb: That's great. I was thinking I needed to fiddle around changing cables when I wanted to use the PC on the Dell monitor, but I can just switch input source.

    This might just turn out just fine!

    Will order a cable from Monoprice, hope they ship to Sweden!

    Thanks all.
  15. theSeb macrumors 604


    Aug 10, 2010
    Poole, England
    No. Thunderbolt uses the physical Mini Display port and the Thunderbolt protocol carries the MiniDisplay port signal. That's why you need an adaptor or a MiniDisplay Port to Displayport cable. Not Display Port to Display Port. That Mini part is important.


    It seems like you're sorted.
  16. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    theSeb: Yes, thanks!

    For anyone interested, Monoprice do indeed ship to Sweden.

    But, it will cost much.

    $3.94 : 3ft 32AWG Mini DisplayPort Cable - White
    $60.38 : Shipping

    Will have to find another place if possible :)
  17. Hexley, Dec 16, 2012
    Last edited: Dec 16, 2012

    Hexley macrumors 6502a

    Jun 10, 2009
    mini Display Port and Thunderbolt Port are essentially the same.

    The difference between the two is that mini Display Port is solely Audio/Visual while Thunderbolt is Audio/Visual + Data. Display Port (found on our U2711) is just physically larger in dimension than mini Display Port and Thunderbolt Port.

    No need for a thunderbolt cable as the U2711 is not designed to pass through data. AFAIK Apple makes the only displays that passes through data.

    Here is the link to the various DisplayPort to Mini DisplayPort Cables. No need for silly adapters or whatnot. Just choose the cable length you want. I chose the 3ft one as I will be putting them side by side.

    Once you have your 2012 27" and U2711 setup take a photo for all of us to appreciate. BTW the iMac has two Thunderbolt ports so you could attach a 2nd U2711 for a triple display setup. :)
  18. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    Hexley: Since shipping costs was $60 from Monoprice, after I checked some other forums, I recently (5 minutes ago) ordered the ACCELL Mini DisplayPort to DisplayPort 1.2 Cable from

    I read a Swedish forum and one dude complained that he bought some cheap MDP -> DP cable and it didn't work good (screen flicker, bad image etc.), so he recommended an A-grade brand and specifically ACCELL.

    And since the shipping costs from to Sweden were much cheaper than from Monoprice, I think I got a better cable for less the cost.

    Yes, I will order the iMac today (haven't exactly made up my mind yet on some configuration options, but it is leaning towards the more expensive options!). On Apple's Swedish website it says they will start shipping in January, so I guess it will take a while until I get it. I will bookmark this specific post page and post some pictures, (hopefully I will not forget this!).

  19. theluggage macrumors 68040

    Jul 29, 2011
    Not really. It's better to think of TB as a dual-purpose port that can work in either Thunderbolt mode or DisplayPort mode, but not both at the same time.

    The Thunderbolt controller chips takes two of the 2-way PCIe bus signals (as used for internal expansion cards in PCs/Mac Pros) and combines it with two DisplayPort video outputs from the graphics chip to produce a single Thunderbolt signal. That signal is not compatible with DisplayPort in any way - it just uses the same physical connector as Mini-DisplayPort.

    However, if you plug in a DisplayPort monitor (or a Mini-DisplayPort-to-VGA/DVI/HDMI adapter) the TB controller detects this, switches off the Thunderbolt signal, and routes the DisplayPort signal directly to the socket.

    The Apple Thunderbolt Display accepts the full thunderbolt signal, and contains the standard thunderbolt controller chip that splits off one of the PCIe channels (to run the soundcard, cameras and interface ports) and one of the DisplayPort signals (to run the monitors). That's why it needs a thunderbolt output & matching cable and won't work at all with a DisplayPort input.

    It also explains the slightly bizarro and annoying restriction that you can't daisy-chain a DisplayPort device directly from a Thunderbolt Display, but can if you connect a TB disc drive between them. The standard TB peripheral chip only extracts one video signal, which the TBD needs to drive its own screen - so it doesn't have a 'spare' signal to drive a legacy DisplayPort device. Plug in a TB disc drive, however, and its controller chip extracts the second video signal from the TB signal and, since a disc drive doesn't need video this can be used to drive a second screen.

    Unlike a TBD, though, an iMac has a video controller capable of driving two or more screens, so it has a 'spare' video signal to drive a displayport device.
  20. Hexley macrumors 6502a

    Jun 10, 2009
    I ordered my 27" on the first week of December. The dealer I talked to said 45 days or less so I am hoping to get mine by mid-January or earlier. I will order my 32GB of RAM the first business day of January as the prices of parts have been steadily rising as we are getting closer to Christmas.

    Seeming we both have the U2711 here is my config. I do a lot of Aperture 3 RAW workflow and looking forward to video work as well.

    2012 27-inch iMac
    3.4GHz Quad-core Intel Core i7, Turbo Boost up to 3.9GHz (Core i7 helps with photo and video processing)
    8GB 1600MHz DDR3 SDRAM - 2x4GB (upgrading using cheaper (4x8GB) 32GB DDR3-1600 3rd party RAM)
    1TB Fusion Drive (I want SSD speeds and I will plug in an external USB 3 HDD or Thunderbolt Drobo 5D)
    NVIDIA GeForce GTX 680MX 2GB GDDR5 (dual or triple 2560x1440 will require a high end GPU to keep things snappy)
    Magic Trackpad (Apple's mouse is meh...)
    Apple Wireless Keyboard (will use it with iPhone and iPad)


    Your explanation is comprehensive and exhaustive but will tend to tl;dr most people.

    My earlier explanation was simpler and appropriate to digest given that the thread starter just wanted to know what cable to use on our iMac and our U2711.

  21. gnasher729 macrumors P6


    Nov 25, 2005
    Thunderbolt works fine as a Mini Displayport. You will not get some advantages of Thunderbolt, like connecting further devices. It could be that you can't attach a Mini Displayport monitor to a Thunderbolt hard drive, for example, but Mini Displayport straight connected to the iMac should work.

    Dual link DVI is expensive, and it doesn't tend to work very well. (Basically, the display signal is split into two DVI signals, and then the monitor combines the signals again. That's just complicated and asking for trouble).
  22. Hexley macrumors 6502a

    Jun 10, 2009
    For Thunderbolt data pass through to work on a Thunderbolt device you will need a Thunderbolt cable. AFAIK Apple and other third party makers only use the miniDP formfactor for their Thunderbolt cables. Which is perfectly fine as devices that uses DisplayPort formfactor are just A/V devices.
  23. theSeb macrumors 604


    Aug 10, 2010
    Poole, England
    I am not aware of any Thunderbolt hard drives with two thunderbolt ports that do not allow you to connect a Mini Display Port to them. Do you know of any?

    The example you stated is only applicable to the Apple Thunderbolt Display. It does not allow you to connect a mini display port device to it. You actually have to add another Thunderbolt port device to the ATD and then you can connect another monitor to the chain via mini Display Port.
  24. gnorknagar thread starter macrumors newbie

    Dec 16, 2012
    Hijacking my own thread just a bit.

    Hexley (and others): I am too planning on 4x8 GB RAM, I made a thread at the Crucial forum. I had read on another forum that Crucials RAM part numbers on their official web shop differ from the part numbers sold by "normal" retail stores, and that seems to be correct. For example, the kit with part number CT2KIT102464BF160B (2x8 - I will get 2 of those kits) is the same one they sell on their official web store.

  25. Hexley macrumors 6502a

    Jun 10, 2009
    I'm adding 32GB to my 27" as well but from a different vendor.

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