New 15" MBP w/TB max GPU option, connected to 2 LG Ultrafine 5k with supplied USB-C/Thunderbolt 3 cable, one on left side of MBP and other on Right side, nothing else connected. MacOS 10.12.2 b2 Issue: All 3 screens start going black randomly. SMC reset PRAM reset Still persists No specific app open Anyone else with above setup, not having issues? Thanks
Dual LG ultrafine 5k black screens intermittent
Update Sierra 10.12.3 B2
Have you tried disabling Automatic Graphics Switching? I found it was causing some issues over here (I have the same setup and a number of graphics issues, but not that one specifically).
Thanks. I did disable auto graphics switching. Same issue. It is totally random. 10 minutes no issues, then a demon has taken over all screens! I even bought the Belkin T3 cables at Apple Store today. No go! As a single external display, no issues. Dual display seems to cause issues. Sierra 10.12.3 B3 updated today... same issues with dual 5K.
Hmm. So, I have an open case for my issue (randomly under heavy GPU load the two displays will flicker on and off with graphics glitches, rather than black). In my case I did the same as you (SMC and PRAM) with no succes, and they also had me dump the caches from the system library (so you might want to try that even though I'm not confident it will help).
Over here, I *think* we've narrowed it down to bad Thunderbolt controllers on one side (I have the issues only when a display is connected to a right-side port). Try connecting both displays to one side (even though I also have a feeling a single controller can't actually sustain two 5K displays despite the machine allowing it) and see if it makes the flicker issue go away. It will add a new issue where you may need to restart to get the computer to even acknowledge the 2nd display, but for testing maybe you can narrow things down.
Sorry you're having these issues too -- will post again next week after they run some hardware diagnostics on the machine. I know someone else who ended up having their machine replaced due to bad TB3 hardware, so I'm starting to wonder if there's a larger-scale issue at play.
Oh, and for record, I'm still running the release version of 10.12.2 over here, so it's not a beta software problem (unless you count their graphics drivers ;P ).
I just fixed a very similar issue by moving my LG 5K Ultrafine away from my WiFi router (they were on the same desk) Just thought I'd let you know...
Yes, 2 new monitors, and a new 2016 TB-MBPr later, moving router 5+ feet away seems to solve issue.
There is a report on appleinsider about lack of shielding on monitor/cable that may be the culprit.
S.