Display Port issue

Discussion in 'Mac Pro' started by z06gal, Oct 21, 2014.

  1. z06gal macrumors 6502a

    Aug 30, 2011
    My monitor will not sleep when connected via DP. The screen goes black but wakes back up in 5 seconds and does this over and over. If I power the monitor off, it will say "no signal detected" when attempting to wake it up. The nMP wakes without issue so it seems to be some sort of communication issue. I was hoping someone here could help. The monitor is an LG 34UM94. The DP is the only input that does this and of course it would be the one I want to use :roll eyes:

    Anyway, if anyone has any idea what this is, I would really appreciate the help. ;)
  2. Chung123 macrumors regular


    Dec 5, 2013
    I had a similar issue with a Dell monitor connected via DisplayPort.

    Try unplugging the display port cable and power cable.

    Now press and hold the LG monitor's Power button a couple of times to "reset" it.

    Plug everything back together and give it a try?

    Worth a shot.
  3. thefredelement macrumors 65816


    Apr 10, 2012
    New York
    I'm on a cMP with an after market flashed ATI card and two display port screens and all sorts of weird issues, I cleared all the caches, reset the SMC, then the PRAM and they've all been happy since.

    I also unplugged my keyboard from one of the screen's USB ports (saw that on some forum somewhere, don't know if it was it or not as I did a bunch of changes at once).
  4. Alrescha macrumors 68020

    Jan 1, 2008
    In case you have not seen this thread, you are not the only one with strange behaviors with this monitor (which is a shame, because otherwise it seems like an awesome piece of gear).


  5. z06gal thread starter macrumors 6502a

    Aug 30, 2011

    I have been keeping up with that thread. I have tried everything recommended and nothing works. I called LG and "No one has ever called with this issue before." Lol So, since thunderbolt works fine I will just use that. It is like there is some sort of miscommunication b/w the monitor and Mac Pro :confused:

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