Macos Sierra, dual Dell P2715Q, MacBook Pro Retina - Monitor flicker issue

Hi,

Did you ever get anywhere with a fix for this?

I have almost the exact same setup as you with exactly the same issue that commenced only with the install of Sierra. It was absolutely perfect before that. I also run at 2560x1440 @ 60Hz on both and can run with the clamshell open or closed with the native screen on or off. Flicker remains in all circumstances. The volume of user activity or thermal/power load seems irrelevant. 10.12.4 to .5 seemed to be a little better (I think they included driver improvements for the 2016/17 models) but 10.12.6 seems to be worse than any OS prior.

Initially I felt this to be an OS or driver issue pertaining only to the frontmost T-Bolt port, as you describe.

Like you I have tried clean installs, SMC reset, NVRAM reset, raised a bug report on the developer site (closed by Apple without action), changed cables, etc. All to no effect.

I have posted on MacRumours and here but had little/no useful response.

Mac OS Sierra: Erratic resolution of Dell 4K P2715Q monitor

Users Report Loss of HiDPI Scaling on External Displays in macOS Sierra | Page 4 | MacRumors Forums

I would be interested to know how you have got on since.

Interestingly, we do have 2 MacBook Pro 2015s at my work with a total of 4 x 4K P2715Q monitors. All of the monitors do flicker with the afflicted MacBook Pro if tested with the same or differing cables.

Weirdly, the second MacBook Pro does not flicker but does get odd graphical issues such as random window alignment where the window get moved off screen and can only be recovered by changing resolution on the affected monitor and then changing it back. Its like the Mac looses the resolution of the screen and misplaces the window. Also the second MacBook Pro runs much hotter than the flickering one. Our MacBook Pros are essentially the same batch from the same order and very close in serial numbers with identical spec. The variation in the flicker profile between them has led me to wonder if there is a driver issue or a batch issue with the T-Bolt port on a subset of MacBook Pros. However the other graphical glitches point to a driver problem as cables and monitors have been ruled out and the older OS (10.11.x just works!).

Re: the possibility of hardware failure, I have AppleCare but have not pursued as yet as I was hoping for software fix or 10.13 to resolve. Alternatively, a total hardware failure would do me fine as the fault is highly random and some days I can go hours without flickering, other times it will flicker every minute or less. Also the kit I have is not easily taken to a nearby Apple Store (120miles round trip!).

I would be interested in hearing your experience so far.

Details:

* MacOS Sierra 10.12.x (issue occurs on any version - now 10.12.6) [Note 10.11.x is fine - no issue].

* MacBook Pro Retina 15-inch, Mid 2015, 2.8 GHz, 16GB, AMD Radeon R9 M370X

* Identical Dell P2715Q monitors bought new at time of MacBook Pro purchase (February/March 2016).

These are connected directly to mac using the included factory Mini DP to DP cables. Cable changed to branded with gold connectors and monitors swapped out with another P2715Q pair to no effect.

* All monitors are REV A03, running at 2560 x 1440 scaled resolution on MacOS and @60Hz. Native Retina display can be used simultaneously with he 2 x 4K monitors or be off without changing the issue.

Two 4K monitors, both at 60Hz, is pushing the envelope (and in a scaled resolution to boot).

I am surprised this even worked in El Capitan.

Here is the relevant knowledge base article - where there is mention of one 4K display at 60Hz, but never of two simultaneously:

Using 4K displays, 5K displays, and Ultra HD TVs with your Mac - Apple Support

Thanks. I did a lot of research before procuring the MacBook Pros and the 4K monitors. The only 2 Macs were capable of running 2 x 4K @60Hz in a sustained manner were the 2015 MacBook Pro and the Mac Pro 2013, the former was the cheaper option. And it did work perfectly pre 10.12 and scaled and @60Hz on 2x 4K and with the Retina display on and that scaled too! It was amazing, well under El-Capitan anyway!

Yeah, I hear you. They changed something about graphical handling I think and it is probably unlikely to change. Its just annoying how it can work for 6-7 months fine then bang...probably should have gone with the Mac Pro instead. 2016 MacBooks weren't out in Feb 2016 and we'd held out for new Macs for years to try and get the right spec and price balance. Ho hum...

Hi.

Just to say that High Sierra (10.13) has been running fine on my 15 MBP and dual 4K monitors since installation. I think I have gone 3 days without a flicker! Currently it is behaving just like it did under El Capitan (10.11), so is a year of flickering over? Fingers crossed....

Let's keep this Q&A alive, because the problem isn't solved yet.

My symptoms: flickering external screen, black "fuzz" band 5 cm wide rising up the external screen, total failure of external screen image ( just goes to black). All of these symptoms within one minute of plugging in screen.

These symptoms are pretty recent, may be related to OS updates, not sure. Same symptoms on both Thunderbolt/displayport sockets.

Installation:

MB Pro early 2015 Retina 13"

High Sierra 10.13.1

Dell U2713HM external screen

Mini Display port on mac to DP on Dell

Actions taken : SMC reset, monitor reset. Monitor works fine on DVI port from my Mac Pro running El Capitan 10.11.6. Any ideas?

P.S. These displays are SST not MST.

I don't know why this worked in El Capitan and not in Sierra.

Perhaps (without getting your hopes too high) it works again in High Sierra?

But...one can hope!