Can't change screen resolution on headless Mac

Discussion in 'Mac Pro' started by scott216, Jan 27, 2014.

  1. scott216 macrumors newbie

    scott216

    Joined:
    Sep 14, 2011
    Location:
    NJ
    #1
    I have a Mac Pro (late 2007) running OSX 10.7.5. I want to remove the monitor and use it headless via Mac's built-in screen sharing (from a brand new iMac). When I screen shared and the monitor was still attached to the Mac Pro, it worked great. But when I disconnected the monitor and screen shared again, the resolution was 800 x 600. I tried changing the resolution, but it won't change to anything other than 800 x 600.
     
  2. Rock Hound macrumors member

    Joined:
    Dec 26, 2013
    #2
    Headless setups seem to default to the resolution of the last display hooked up to the Mac. I have a mini hooked to my TV, so it displays as 1080i on any remote computer. My oMP was hooked to a 2560 x 1600 display on one head and a 1280 x 1024 resolution; both displays showed up at full resolution when screen sharing. When I got my nMP, I disconnected both displays and was stuck in 1280 x 1024.

    My advice is to hook the computer to the highest resolution display you have access to, and it will probably keep that resolution when deployed headlessly.
     
  3. VirtualRain macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #3
    With my usually headless 2011 Mac Mini connected to my TV. Unless the TV is on, the Mac Mini will open a desktop sharing session at like 1680x1050.
     
  4. Buckeyes1995 macrumors member

    Joined:
    Mar 4, 2011
    #4
    Google for 'headless mac resistor'. You can hook a VGA adapter and short two pints with a 80ohm resistor to fake the mac into thinking you have a monitor attached so OSX loads the appropriate drivers. This works for all old models.
     
  5. scott216 thread starter macrumors newbie

    scott216

    Joined:
    Sep 14, 2011
    Location:
    NJ
    #5
    I just tried that with three 100-ohm resistors. Unfortunately it didn't work. Searching the web it seems to be a common solution to this problem. I wonder if it's something that works better on a Mac Mini then Mac Pro.
     
  6. scott216 thread starter macrumors newbie

    scott216

    Joined:
    Sep 14, 2011
    Location:
    NJ
    #6
    I tried 68-ohm and that doesn't work either. Just to add some more info: there are tons and tons of resolutions listed in the display dialog box. But when I choose one nothing happens for 30 seconds or so, then then the highlighted resolution goes back to 800 x 600 in the dialog box. I don't see any sign of the display momentarily switching resolutions.
     
  7. scott216 thread starter macrumors newbie

    scott216

    Joined:
    Sep 14, 2011
    Location:
    NJ
    #9
    It seems to be working now. I clicked on a higher resolution, and before it reset back to 800 x 600 I pulled the display plug out of the computer. Then the resolution changed. When I plugged it back in, it kept the higher resolution. I'm not sure what's going on, but I think I have a workable solution at the moment.
     

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