DELL U2711 Monitor Resolution with iMac 2010

Discussion in 'iMac' started by deacLL, Apr 4, 2011.

  1. deacLL macrumors newbie

    Joined:
    Apr 2, 2011
    #1
    I can't get my new DELL U2711 27" monitor to achieve 2560x1440 resolution with my iMac 27" Fall 2010. Nothing higher than 1920x1080 which I could get for a lot less money than the U2711. ;-)

    I updated all iMac software.

    Is this likely to be a cabling problem, driver, other?

    Thanks much,
    Deac
    ;-)
     
  2. alust2013 macrumors 601

    alust2013

    Joined:
    Feb 6, 2010
    Location:
    On the fence
    #2
    Most likely a cable problem, unless you have a miniDisplayPort to DisplayPort cable running it. How do you have it set up?
     
  3. Drewbie macrumors member

    Joined:
    Aug 27, 2010
    #3
    the max resolution for an analog cable setup is 1920x1080
    a digital setup will be the 2560x1440 you are looking for.

    so as the above poster has mentioned its most likely a cabling issue.... can you do an minidisplay port to HDMI ? or are you doing a minidisplay port to vga/dvi
     
  4. drambuie macrumors 6502a

    Joined:
    Feb 16, 2010
    #4
    A good quality shielded VGA cable can easily handle 2560x1600, which is the resolution used by some 27" 16:10 LCD monitors. Analog VGA can reach QSXGA resolutions of 2560x2048, which is the resolution of some very high res 5:4 CRT monitors. Most recent average graphics cards can output up to 2560x1600, or beyond, via VGA. The analog bandwidth for a 2560x1440 x 10 bit signal is 110.6 MHz. A good quality VGA cable will do ~400 MHz.

    For an actual product reference, the Dell Ultrasharp U2711 mentioned by the OP will run at 2560x1440 via VGA input.
     
  5. deacLL thread starter macrumors newbie

    Joined:
    Apr 2, 2011
    #5
    Solution found

    Thanks much to all the folks who provided the answer and insights to the answer. I'll summarize what I found and my current solution.

    According to the User Guide (which I finally obtained), the only cables that support 2560x1440 into the DELL U2711 are these two inputs:
    - Dual Link DVI, or
    - DisplayPort

    I bought a $99 miniDisplayPort to Dual LInk DVI which in fact does the job. I have a $10 miniDisplayPort to DisplayPort on order from Amazon.

    I tried regular DVI , HDMI, and VGA inputs all of which failed. This point is (now that I found it) supported by the User Guide info which says:
    Set the screen resolution to 2560 x 1440 (DVI and DisplayPort)
    or 2048 x 1152 (VGA) or 1080p (HDMI, Component)
    Somewhere it says that the DVI must be dual link. Wasn't obvious to me at first.

    THANKS SO MUCH FOR YOUR HELP. I SPENT 3 DAYS TO FIND WHAT, IN THE END, IS A VERY SIMPLE ANSWER.
    HAPPY HAPPY HAPPY.
    :) :) :)
     
  6. Drewbie macrumors member

    Joined:
    Aug 27, 2010
    #6
    im sure the monitor will support that, but the computer will not if its VGA. either way they got it working...
     

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