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After upgrading to Yosemite, I see just noise on the external monitor, using a MDP to HDMI converter and an HDMI to DVI cable. It worked very well on Mavericks. I have no display now after updating, it just shows grey noise. Tried resetting SMC & PRAM. Additionally, I have tested each of the cables individually and they are okay, so it has to be a software problem.

Display screenshot:

This is what my display looks like

It shows flickers in red color sometimes.

Macbook gives display on another setup, but flickers a lot. (my friend's) its a MDP to VGA adapter plugged to VGA monitor.

Mine gives no display, I'm disappointed. Need help please.

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  • Does it show up in Display profiles in About this Mac and in ColorSync Utility app?
    – Ruskes
    Oct 27, 2014 at 19:50
  • You're not alone. discussions.apple.com/message/26885684 Oct 28, 2014 at 9:16
  • yes it does show up everywhere
    – Syed Usman
    Nov 8, 2014 at 12:09
  • I have this same problem and have yet to find a solution. MBAir 11" 2014, with Mavericks the external monitor via Thunderbolt to DVI worked fine, after upgrading to Yosemite I get the same thing as Usman... My monitor works fine if connected on startup, but after sleep, or disconnect/reconnect, it goest to this noise display... annoying!
    – MOK9
    Jan 15, 2015 at 10:42
  • 1
    Plugging the cable out and in again fixes it for me, but that can't be a permanent solution
    – Niall
    Apr 8, 2015 at 11:55

2 Answers 2

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You can reduce the display resolution to 720p (or any else, feel free to experiment). It might be a working solution.

To do this follow these steps

  • Open system Preferences > Displays
  • Choose lower resolution from list
  • If you want a higher resolution for your external monitor, you can try to use third party software (e.g. SwitchResX) to change it
1
  • Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Apr 11 at 5:41
1

UPDATE

I almost forgot I had this issue, recently I changed cables. I am now using MDP to HDMI without adapters. Before I am using DVI to DVI Cable + DVI to MDP Adapter.

I think you need to avoid 2 conversions and use only 1 cable.

OLD ANSWER

It is also happening to me, and I can't find the solutions either. But I figured out how to avoid it.

When booting up mac

  • turn off monitor first and then power on the mac.
  • turn on the monitor after the mac finished boot or in the login screen

Settings

  • Open system Preferences > Energy Saver
  • Click Power Adapter tab(assuming your mac is plugged in) and slide the 'Turn display off after' to at least 1 hr.

It also occurs when mac goes to sleep and to avoid it, the steps above should be followed. Only do the settings step if you don't mind the power consumption.

Please let me know if you have better suggestions but this works for me as of now.

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