Syncmaster SA650 external display blanks out intermittently

Hi, ninequeens!

Thanks for using the Apple Support Communities. After reading the information you provided, I see that you are having some trouble with your Samsung Syncmaster external display. I know how convenient having an external display can be, and want to make sure yours is working as it should. I've got some troubleshooting you can go through to help.

I'd suggest getting started by going though the article linked below.
Get help with video issues on external displays connected to your Mac
If you're still having trouble with your display after going through that article, I would recommend checking with Samsung for any firmware updates that may be available for your display. Once you're sure you have the latest updates from Samsung, you can then try the following steps if the issue continues.

1. Turn off your external display and your MacBook.
   
2. Disconnect everything connected to the MacBook (including disconnecting any adapters from each other), then reconnect them.
   
3. Reset the computer's System Management Controller. The article linked below will provide information on what the System Management Controller handles, and instructions on how to reset it. You'll want to follow the steps under the "If the battery is non removable" section of the "Reset the SMC on Mac notebook computers" heading.
   
   Reset the System Management Controller (SMC) on your Mac

Have a lovely day!

Hello,

i have the same problem with the new Macbook 12" 2016.

With several displays and several USB-C HDMI adapters the external display show up a black screen every few seconds.

More in this thread: Re: Macbook - problems to connect w external screen