macOS Sierra can't detect 2560 x 1440 monitor resolution correctly

No, lowering the refresh rate does not open up any additional resolutions with the BenQ2765 monitors via HDMI to HDMI

I have the same monitors and the same problem. Do you also get a weird error message when booting up with both external monitors plugged in?....mine just gets stuck in an endless starting up, error, reboot and repeat cycle..unless I do the reboot with the monitors not connected and then plug them inline after OSX Sierra is up and running and all happy.

Hello,

I just updated to 10.12.1 Beta 4 and it solved this issue.

Maybe you should register to the Beta program.. it's free.

Cheers,

Fred

I have the same problem with my Philips 272B4Q monitor since I updated to Sierra. I can't get an higher resolution than 1080i. The resolution and size of the monitor in the image below are not correct.

In my office I have 2 Mac mini's from late 2014 which I also updated to Sierra and connected to the same Philips monitors and they don't have problems.

The resolutions and size in the image above is correct.

I also tried a SMC reset. Didn't help...

I filled a bug report.

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.

This happened to me with a 4K monitor. At first macOS Sierra saw all the resolutions available from 4K down to 640x480. Then all of a sudden all the resolutions disappeared from the display menu except 4K and 1080. Of course I couldn't use 4K because there's no way to increase the system fonts to a larger size. I wanted a resolution higher than 1080 though. I ended up erasing the hard drive in disk utility and doing a clean install of macOS Sierra (not the beta). I can now see all the resolutions available on my monitor from 4K all the way down the line. Hopefully the options don't disappear again, but a clean install of macOS fixed it for me. This is definitely some kind of bug that needs working out.

Same here on a Dell 4K screen. One resolution is too low, other one too high. The resolution I previously used is gone...

The problem is fixed with my Macbook Pro since the 10.12.1 update. 🙂

Upgrading to 10.12.1 solved the issue for me

Thx all. Latest update also did it for me.

I have the same problem.

😮 I do not understand that could happen !!!

Upgrade to version 10.12.1 Solved it for me

I have an acer k272hul :

L'Acer K272HUL est un moniteur en WQHD (2560x1440 px). L'occasion pour nous de tester une dalle AHVA, une technologie IPS — malgré une dénomination VA trompeuse — que nous n'avions pas encore testée car relativement rare.

I upgrade to 10.12.1AND IT DOESNOT WORK !!!

I donnot understand how can this could happen !!!

Have you tried a DisplayPort cable. Some user have had luck using DisplayPort vs HDMI

File a bug

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

Make sure you tell them you are using 10.12.1

Give them exact make/model monitor.

Give them the exact make/model cable you are using, and any adapters you are using.

If there are any error messages, give them the exact wording of the errors.

If the monitor is working, but not at the resolutions you need, tell them what resolutions are available.

They may close the bug as a duplicate, but it may also give them some unique information to help them resolve the issue. And even a closed as duplicate bug is a factor when management assigns priorities to a problem.

Thanks for your answer.

Make sure you tell them you are using 10.12.1 : I did

Give them exact make/model monitor. ACER K272HUL

Give them the exact make/model cable you are using, and any adapters you are using. Apple HDMI (it was correctly working before the sierra update !)

If there are any error messages, give them the exact wording of the errors. no error

If the monitor is working, but not at the resolutions you need, tell them what resolutions are available. the resolution is 1900 x 920 (if I remember)

They may close the bug as a duplicate, but it may also give them some unique information to help them resolve the issue. And even a closed as duplicate bug is a factor when management assigns priorities to a problem. THIS BUG IS REAL !!!