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

Definitely.

http://superuser.com/questions/1116866/macos-sierra-doesnt-scale-for-4k-monitor/ 1126490

But there's no workaround so far other than rolling back to El Capitan. Apparently, it will take a new Sierra release with an updated video driver to fix this problem.

What I can't discern from the various Internet posts so far is whether this problem is peculiar to the MacBook or occurs on all Macs.

I have an iMac, and I don't see anyone explicitly describing this problem on my hardware as yet. However, I depend on my Dell P2715Q too much to risk upgrading to Sierra until this question is answered.

Everyone that has these monitor resolution problems should file their own Bug report with Apple so that they know that each and every one of you is having these problems. Depending on one person filing a bug and hoping Apple will do something about it is not sufficient.

BugReporter (Free ADC (Apple Developer Connection) account needed for BugReporter)

<http://bugreporter.apple.com>

Anyone can get a free ADC account at:

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I'm currently having 1-2 kernel panics per day,

Kernel panics are often times the result of 3rd party additions. I would suggest you start a separate new "Post" just for the kernel panics, posting the output from a few of the panic reports in the new Post. Do not do it in this thread, as that will just confuse and dilute the monitor issue.

Kernel Panic reports: Finder -> Go -> Go to Folder -> /Library/Logs/DiagnosticReports

<http://support.apple.com/kb/ht2546>

<http://support.apple.com/en-us/HT200553>

The panic report should have "panic" in the file name.

Also in the new Post, you might include the EtreCheck output, which is often times helpful

<https://discussions.apple.com/docs/DOC-6174> or <http://etrecheck.com>

Hi,

I am running 2 x Dell P2715Q on a Mid-2015 15 inch rMBP. Both are on display port connections into separate TBolt ports.

On 10.11 (El Capitan) these both ran @ 60Hz no issue in either 'retina' mode (like 1080p) or any scaled resolution up to 3840 x 2160 on both displays. I typically run in the "looks like 2560 x1440" scaled mode. It matches what I am used to in non-retina iMac 27 inch terms. Both monitors would also run with the normal retina display on or off (in clamshell mode), again without glitching.

I upgraded to 10.12 (Sierra) without issues on every other mac I own (I have a fair few) but this rMBP has been a pain in the arse. I have scaled resolutions as normal (I don't have the scaling trouble others have had) but at any scaled setting one of the monitors goes blank intermittently and is then reacquired. This is unpredictable and is not the same as being unplugged, i.e. the open windows don't migrate like a single monitor situation. An SMC and NVRAM reset do nothing. I considered some form of thermal GPU throttling/GPU switching as possible causes but forcing dedicated graphics use doesn't seem to help (unselecting automatic graphics switching in energy saver preference pane), although it may increase time intervals between the blanking periods. It's not hardware based as if I swap ports over the other second monitor blanks intermittently instead. Finally a time machine restore to 10.11 resolves the issue. This is clear a 10.12 (Sierra) fault in my opinion.

I am not sure if there is thermal problem relating to more stress on the hardware from 10.12 as I seem to have the fan running more than 10.11. I have noted more glitching and pausing in activity, especially shortly after boot and particularly on the rMBP. Other machines have paused similarly too and had occasional screen image glitches when under stress.

Finally, I also think the blanking periods on the rMBP are more frequent under stress, like when using chrome to stream BBC player content. Perhaps the OS is taking more out of the GPU that the prior version?

Any ideas for a fix?

I've no "fix," but I would suggest one further troubleshooting step, perhaps not an easy one. As prior posts in this thread all reference trouble with the specific monitor you (and I) have which started with the Sierra upgrade, I'd like to know if your issue is related directly to the P2715Q. Do you perchance have access to another brand of 4K monitor that you could insert in place of the P2715Q that's malfunctioning?

Unfortunately not, I only have access to Dell P2715Q monitors, we have 4 in my immediate vicinity. Changing these around has no effect. We don't have any other 4k monitors at present.

The cyclical blanking/black screen is very variable. I have been timing it and current the gaps between episodes varies between 3min 25secs up to 47min 56secs. I cannot really spot any difference in working practice with the machine over the period that would force the event, its all so frustratingly intermittent.

I feel it is probably GPU load based but have yet to prove it. I can swap the screen affected around based on cable swapping, I therefore think it is restricted to the one tbolt port (front most one next to the USB3.0 port on the left).

I cannot see how it is a hardware failure as 10.11 is fine.

I also wonder whether the automated graphics switching is running regardless of setting in the preference pane. My theory is that the discrete GPU is shutting down (?thermal related) and there is a reversion to the CPU integrated GPU which cannot run both thunderbolt ports for display. When this happens one display/port shuts off but not in a manner to register it at the OS level to move to a single desktop display mode. In the fractions of a second when only one screen is black the discrete GPU/port comes back on and I am back to two functioning displays again. There is never a scaling issue and the display always returns at the right setting.

Perhaps it is a driver issue or a GPU regulatory issue.

It could also be more aggressive power saving on the rMBP under 10.12 vs 10.11 despite being on mains power and having energy saving options disabled. I wonder if there is a terminal command control for GPU switching?

gfxCardStatus is a free menu bar application that keeps track of which graphics card your MacBook Pro is using at any given time, and allows you to force select which GPU to use.

<https://gfx.io/>

macOS Sierra 10.12.1 was just released.

Some beta users reported their monitor issues were resolved.

Suggest if anyone in this thread is still using Sierra, that they try the 10.12.1 update.

Thanks. It had no effect.

Thanks. This also has no effect. In fact I think it probably is slightly more frequent now. Ho hum...must be something simple. I think I may go back to 10.11 again.

I suggest you follow through and report this as a bug to Apple

BugReporter (Free ADC (Apple Developer Connection) account needed for BugReporter)

<http://bugreporter.apple.com>

Anyone can get a free ADC account at:

<https://developer.apple.com/register/index.action>

Be sure to tell them you are still having problems with 10.12.1, so they do not lump it into all the monitor reports about not supporting all sizes on 3rd party monitors.

Thanks I have done so.