macOS Sierra External HDMI display not showing 2560 resolution

ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
Hi I was wondering if anybody could give me some pointers.

I've just upgraded my 2015 MBP to Sierra and plugged in my ASUS PB278 27" 2560x1440 monitor, except that resolution is no longer available, even when option clicking the scaled radio button in system preferences.

My friend has the exact same setup as me, MBP and monitor, purchased at the same time and he has 2560x1440 instantly available. I've tried clearing the PRAM and a different HDMI to HDMI cable and neither have fixed it.

Any pointers would be extremely greatly received as I'm struggling to work on it at the moment.

Thanks in advance
Thom
 

Donka

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May 3, 2011
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Weird. I have the exact same Spec rMBP but haven't upgraded yet for this very reason. I know my Mac Mini would not support 1440p over HDMI but it works fine via Mini DP - that is still on El Capitan as well for the time being.
 

raggal

macrumors newbie
Sep 21, 2016
2
0
France
Same problem here with an Acer X34 (21:9 UltraWide WQHD 3440 x 1440) on a retina MacBook Pro via HDMI.
With El capitan I had the option to go much higher than 1080P. On macOS Sierra I just have the choice of 1080p as highest resolution option. (tried with option pressed + scale too).
 

Donka

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May 3, 2011
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I'm assuming a Mini DP to HDMI cable would work okay given people don't have this issue via a Thunderbolt dock. Means a new cable purchase but if you are stuck with HDMI on the monitor because there are no DP ports (unlikely) or they are already in use, that is an option in the interim.
 
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Donka

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May 3, 2011
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I have a mini DP to HDMI cable so I will give this a try this evening to confirm. My Mac Mini can output 1440p over DP but not HDMI. I'll check Mini DP to HDMI gives 1440p. This would confirm the issue is purely on the HDMI output so Mini DP to HDMI on the monitor side should still work.
 
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ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
I have a mini DP to HDMI cable so I will give this a try this evening to confirm. My Mac Mini can output 1440p over DP but not HDMI. I'll check Mini DP to HDMI gives 1440p. This would confirm the issue is purely on the HDMI output so Mini DP to HDMI on the monitor side should still work.
I've just tried a DP to HDMI connector with my HDMI lead and I've got to the same issue :( this isn't an official Apple connector though, so it could be an issue with the connector not the workaround
 

Donka

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May 3, 2011
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I've just tried a DP to HDMI connector with my HDMI lead and I've got to the same issue :( this isn't an official Apple connector though, so it could be an issue with the connector not the workaround
Was it Thunderbolt (Mini DP) adapter to HDMI adapter and then the HDMI cable into the monitor?
 

dpvis

macrumors newbie
Sep 21, 2016
2
0
Same issue for me. Just upgraded to Sierra and now am stuck using 1080p with my Acer G257HU. Should be able to use HDMI to HDMI, as that is what I was using prior to Sierra and got 2560x1440 no problem. I'm using an early 2013 Retina MacBook Pro.
 

Donka

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May 3, 2011
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Yup, hope Apple get flooded with bug reports for this issue as it clearly needs addressed as a priority.
 

Donka

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May 3, 2011
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Scotland
Yep, was thunderbold adapter to HDMI and then a separate HDMI to HDMI lead
Thanks for confirming. Strange that others have had success with an HDMI connection using a Thunderbolt dock. The only other variable I can think of is the HDMI cable itself. I believe the HDMI cable must be v1.3 or later to support 1440p.
 

ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
Thanks for confirming. Strange that others have had success with an HDMI connection using a Thunderbolt dock. The only other variable I can think of is the HDMI cable itself. I believe the HDMI cable must be v1.3 or later to support 1440p.
Im using the same HDMI cable I was before with el cap and it ran 1440 fine before, no hardware has changed so its got to be an OS issue
 

ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
I've just purchsed a displayport to HDMI cable to see if this solves the problem and it doesn't unfortunately
 

Donka

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May 3, 2011
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When you try it, do you connect everything up first before booting up your machine and turn on your monitor?
 

ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
When you try it, do you connect everything up first before booting up your machine and turn on your monitor?
Ive tried both ways, nothing plugged in and everything plugged in, doesn't seem to make a difference - Im thinking about partitioning my HD and doing a fresh install there just to see if its a legacy pref on my main install causing an issue.
 

ThomRimmer

macrumors member
Original poster
May 29, 2010
40
1
Ive tried both ways, nothing plugged in and everything plugged in, doesn't seem to make a difference - Im thinking about partitioning my HD and doing a fresh install there just to see if its a legacy pref on my main install causing an issue.
I can confirm that a fresh install did not fix the issue - COME ON APPLE SORT THIS OUT!!!
 

Gatortomk

macrumors newbie
Sep 23, 2016
2
0
Just installed the 10.12.1 Beta 4 and it solved my problem. I have an LG UltraWide 29in monitor that has a natural resolution of 2560X1080, but it would only do 1080p after I loaded Sierra. What a relief!
 

slughead

macrumors 68040
Apr 28, 2004
3,104
236
Just installed the 10.12.1 Beta 4 and it solved my problem. I have an LG UltraWide 29in monitor that has a natural resolution of 2560X1080, but it would only do 1080p after I loaded Sierra. What a relief!
I can confirm that a fresh install did not fix the issue - COME ON APPLE SORT THIS OUT!!!
This appears to be a very common issue for people--perhaps everyone with > 1080p running over HDMI. It also sounds like 10.12.1 will fix it. I have tried literally every solution I could find: The command line changing DisplayResolutionEnabled, forcing an EDID file, using a Displayport -> HDMI, resetting PRAM (IMO placebo anyway), etc.

I have a 34 inch 3440x1440 and have been very annoyed running it in 1080p for the last few weeks. Displayport works but for my use-case I'd prefer not to. I agree with Rimmer: SORT THIS OUT!
[doublepost=1476711788][/doublepost]Some rumor sites say 10.12.1 may be released by the end of October, FYI.
 
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nnick2

macrumors newbie
Oct 6, 2016
2
0
I was running two 30" Apple Cinema Display's over one thunderbolt cable using a dock and a Active 4K-HDMI to Displayport converter, so basically:
Thunderbolt -> Thunderbolt Dock -> HDMI to Displayport -> mDP to DL-DVI -> ACD
_________________________ \ -> Thunderbolt Drive -> mDP to DL-DVI -> ACD

This was running perfectly fine on El Capitan, but after upgrading to Sierra the HDMI connection only shows a 30" ACD at 1280x800 instead of the full 2560x1600.
So it does look like they've done some work on HDMI drivers.
Using the other thunderbolt port for that second display solves it for now, but really hope they fix it and I get my thunderbolt port back.


I'll try upgrading tonight to see if that fixes the HDMI problems.
 
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