Digital snow on external screens Macbook Pro 15" 2016 + USB-C Adapter I have this new Macbook pro and this is what is going on after a while. Might be actually a heating issue since I run it in a clamshell mode. But since I can screenshot it I can assume this is a software problem. 





It happens when two monitors are plugged in and I think especially after I scroll or open many windows.

After you let it idle it goes back to normal I will check the GPU temperature next time. The strange part is I can screenshot the issue. So I guess that might be drivers fault? The OS is the latest one: Sierra 10.12.4 (16E195) with all updates installed.

It is probably not related to the temperature:



And the hardware test did not find any defects.

UPDATE

After observing it, I think I could say that it happens only with external monitors connected through Apple USB-C -> USB/Lightning/HDMI adaptors.

But the problem is not in the adaptors or I wouldn't be able to screenshot it.

Update
This looks like a hardware GPU problem.  You can run diagnostics by booting the machine while holding D.  Instructions here: https://support.apple.com/en-us/HT202731

Since this is a pretty new computer I'm sure it will be repaired under warranty (new logic board).  Schedule a genius bar appointment.