I am connecting an external monitor to a MBP with a MiniDP-DVI adapter to which I connect a DVI cable going to a monitor.

The monitor usually doesn't wake up from sleep. I have been unable to use the monitor and gave up for a couple of months. I then used the exact same cable combination and the monitor successfully for two days in a row (a couple of days ago). Now I can't get it working once again. The monitor in question is Dell U2311H.

I noticed a couple of things:

  • once I connected a USB mouse to a MBP, there was 2 seconds of blue screen on Mac screen (not sure but it might have also been blue on the external monitor).
  • if I disconnect the DVI cable from the adapter and reconnect, 2 seconds of blue screen are shown on Mac, but external monitor doesn't react
  • unplugging and plugging the adapter-cable combination does nothing
  • resets don't help

Is there a procedure to get this working (e.g. unplug cables, restart, plug again)?

  • Does the monitor have multiple inputs? Are you sure the monitor has the correct input (also called source) selected?
    – Jonathan.
    Mar 26, 2012 at 8:09
  • @Jonathan. Yes, it has. Yes, I am (but should not be relevant, as it worked one day and stopped the other. I think the input hasn't been changed in the meantime).
    – ipavlic
    Mar 26, 2012 at 8:31
  • Have you tried another monitor? Mar 26, 2012 at 8:57
  • @Lyken Why would I? It was working for two days with Mac, and it still works on Windows.
    – ipavlic
    Mar 26, 2012 at 9:54
  • is this a Dell monitor by chance? |There is a big issues with compatability between Dell monitors and Macs running Lion. See this question apple.stackexchange.com/questions/31178/… Mar 26, 2012 at 10:34

2 Answers 2


There is probably something wrong with the adapter cable. When it's straightened out, and the monitor is connected after the system has started, everything is working okay. I've tested that for a couple of weeks now.


I know from experience that this cannot be fixed. There is a big compatability issue with OSX Lion and some Dell monitors. I used a MacBook Pro on Snow Leopard with a Dell monitor just fine. I upgraded to Lion, and now it doesnt work at all, hoiwever the monitor works with other computers (PC's)

My advice here is to take the macBook and monitor into an Apple store and get them to have a look, there may be a chance someone can get it to work, but not in my local store sadly.

Failing that, you may need to buy a different monitor.

  • I'm hoping that, since it did work for two days in a row, I might find the exact sequence.
    – ipavlic
    Mar 26, 2012 at 11:12
  • I've managed to get it working again for a few seconds by repeatedly plugging and unplugging the cable. Hopefully something is wrong with the cable. I'll take it to Apple store.
    – ipavlic
    Mar 27, 2012 at 7:28
  • And now it's working again full time. I've straightened the adapter cable and poked around with the connectors. Other than that I made no other changes.
    – ipavlic
    Mar 27, 2012 at 19:49

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