macOS 14.1 - No more HDR on 4K monitors

[TinyMito]

After updating to 14.1 - I lost the ability to turn on HDR for the following scales:

2560 x 1440
3008 x 1692
3360 x 1890

But I can still turn on for 1080p or 2160p. Before in 14.0 - I can turn on HDR on any resolution. I am running on USB-C D-Alt Mode through Caldigit Element Hub TB4. Same issue and on top if the HDR is on, all the HDR contents are not enabled, ie. YouTube on Safari.

 

[shuyama]

Me too. I have the ASUS PG32UQ connected directly to the TB port of my MacStudio with a 40Gbps USB-C to DP converter cable and I get the exact same situation: 2560 x 1440 up to 100Hz, 3008 x 1692 and 3360 x 1890 up to 60Hz, HDR items appear, but not at all resolutions and all refresh rates as before. I have tried connecting via HDMI, but the refresh rate for each resolution is capped at 60Hz.

 

[mwdiers]

Same issue on my Cooler Master GP27-FUS. HDR option is gone @4K unless you set refresh to 60Hz.

 

[oberrz]

same with GP27-FUS

 

[a2flo]

Also on a GP27-FUS here.

Played around with smooth scaling resolutions in BetterDisplay:
Fixed 120Hz: max scaled HDR res is 2432 x 1368
Fixed 144Hz or VRR (48-144Hz): max scaled HDR res is 2208 x 1242

 

[oberrz]

Also on a GP27-FUS here.

Played around with smooth scaling resolutions in BetterDisplay:
Fixed 120Hz: max scaled HDR res is 2432 x 1368
Fixed 144Hz or VRR (48-144Hz): max scaled HDR res is 2208 x 1242

Thanks a lot, that works!

 

[stevemr123]

Interestingly this was an issue with M2 Pro/Max up until 14.1 with the exact same resolution and refresh rate cutoffs as @a2flo mentioned. Now with 14.1 my M2 Max Studio has HDR for all resolutions and refresh rates, but my M1 Pro MBP is broken.

 

[matthewadams]

Also on a GP27-FUS here.

Played around with smooth scaling resolutions in BetterDisplay:
Fixed 120Hz: max scaled HDR res is 2432 x 1368
Fixed 144Hz or VRR (48-144Hz): max scaled HDR res is 2208 x 1242

Can you tell me what exactly it is you did there?
Having the same issue with a Gigabyte M32U.

Still cant seem to switch on HDR @ 3520x1980@120hz anything other higher than 60hz

 

[dim_]

Yet another "me too" here. Tried Sonoma 14.2.1, where my M1 Macbook Air is connected to a MSI Optix MPG321UR-QD monitor. With Ventura 13.6.3, all resolutions up to 4k are supported, using 144 Hz refresh rate, and HDR. With Sonoma 14.2.1, the 2560x1440 and 3008x1692 resolutions no longer work with HDR. (It does work with 1920x1080, 2048x1152 and 3840x2160 though). This is a very strange bug, I would expect HDR to work for all resolutions, or not work for any resolution.

Can you tell me what exactly it is you did there?
Having the same issue with a Gigabyte M32U.

Still cant seem to switch on HDR @ 3520x1980@120hz anything other higher than 60hz

What you do is install BetterDisplay, turn on the "Smooth Scaling" feature (see https://github.com/waydabber/BetterDisplay/wiki/Fully-scalable-HiDPI-desktop), by first enabling "Edit the system configuration of this display model", then "Enable smooth scaling", then apply the configuration changes and reboot.

Afterwards, if you click on the BetterDisplay menu bar icon, it should drop down a menu, where you can slide the resolution bar from 100% smoothly up to about 200%. E.g. it allows you to have more 'steps' between the scaled resolutions. However, even with BetterDisplay installed on Sonoma, I still could not get the resolution higher than 2208x1242, before the operating system decides to suddenly turn off HDR.

 

[dim_]

Btw, in the end I gave up and went back to Ventura, as I really cannot stand non-HDR anymore. I will try new Sonoma releases in a separate macOS installation first, before upgrading my main installation, from now on!

 

[johnnymiller100]

Just replaced my monitor with an ASUS PG42UQ OLED and ran into this exact same issue on my M1 Max MBP using thunderbolt to DP1.4 port.

Highest res I can maintain 120hz and HiDPI is 2304x1296, at 100hz it's 2560x1440. anything above that requires a drop to 60hz - havent done much tweaking this is just with better display, so perhaps there is a fix by butchering plists?

Pretty crap, don't get this with Windows. Reading the thread and other Reddits seems to suggest this only started with 14.1. Tempted to go back to Ventura same as the above poster.

Given it used to work I'm hopeful they will resolve it..... but who knows....

 

[dim_]

Note that I have installed Sonoma into a separate APFS volume, booted into it, and then proceeded to use Apple's Feedback Assistant to report this as a bug. I hope other people can also do this, even though it is sometimes very hard to get Apple's attention... (I.e. Feedback Assistant is the only official Apple "bug reporting" tool, but it seems like any report that goes in there is sucked up by a black hole somewhere. )

 

[johnnymiller100]

I'll do similar once I've created a Ventura installation and proven it's not my screen or cable.... between this and the HDMI 2.1 thread it seems apple needs to up their game on external display handling.....

 

[dim_]

I have just installed Sonoma 14.3 beta 2 onto my Sonoma volume, but there was no change in the buggy HDR behavior. So I am expecting no fix in 14.3 anymore. Maybe 14.4, or macOS 15

 

[dim_]

Hmm, this is rather disappointing, but I received an answer from Apple for my Feedback Assistant request:

Hello. Unfortunately, there is a frontend bandwidth limitation that prevents us from reliably supporting HDR at high refresh rates beyond a certain screen size, so we have had to gate the feature slightly more conservatively than in earlier builds of the OS.

Thank you for your feedback.

So my guess is: it's not going be fixed. :-/

 

[TinyMito]

Yeah there 1440p is no longer support HDR, but if you lower it by one resolution down. You can still have HDR just a slight bigger UI. Actually, I do not mind, maybe the text is a tiny bit blurrier.

 

[Jashi]

Hmm, this is rather disappointing, but I received an answer from Apple for my Feedback Assistant request:

So my guess is: it's not going be fixed. :-/

Funny they say that when it seems to work on M2 macs but not on M1 macs as stevemr123 mentioned. Hopefully at some point they will realize their mistake. Maybe stevemr123 could give feedback with these details, it would be interesting to see what they think about this.

 

[stevemr123]

The limitation is refresh rate and framebuffer size dependent (so what seems to matter is the framebuffer pixel clock). Not sure why Apple did it especially as everything seemingly worked just fine for 2+ years and everybody was happy (except for some people complained about a 8bit reported framebuffer color depth but that was a small minority, most ppl did not care). This same limitation applied to M2 initially (probably due to the M2 green screen of death bug) while M1 was unlimited (which was awkward as the older chip seemingly did better than the new one). When they fixed the M2 they also limited M1 (in the same move) - this indicates that probably the same engineer (or maybe a group of engineers) made the changes to both chip firmwares (the capabilities should depend on the rtOS - firmware - version running in a dedicated component of the Apple Silicon chip called "DCP"). Multiple (rather vague) replies from Apple support implies that the limitation is intentional and is here to stay but it would be great if the guys actually making the change explained things a bit better.

Note: you can make 120Hz HDR work up to 2432x1368 HiDPI (you can use BetterDisplay to unlock that resolution) which is slightly higher than the stock 2304x1296 mentioned here. Would have been better if the engineers pushed a bit harder and allow 2560x1440@120Hz HiDPI for HDR.

 

[sashavegas]

The limitation is refresh rate and framebuffer size dependent (so what seems to matter is the framebuffer pixel clock). Not sure why Apple did it especially as everything seemingly worked just fine for 2+ years and everybody was happy (except for some people complained about a 8bit reported framebuffer color depth but that was a small minority, most ppl did not care). This same limitation applied to M2 initially (probably due to the M2 green screen of death bug) while M1 was unlimited (which was awkward as the older chip seemingly did better than the new one). When they fixed the M2 they also limited M1 (in the same move) - this indicates that probably the same engineer (or maybe a group of engineers) made the changes to both chip firmwares (the capabilities should depend on the rtOS - firmware - version running in a dedicated component of the Apple Silicon chip called "DCP"). Multiple (rather vague) replies from Apple support implies that the limitation is intentional and is here to stay but it would be great if the guys actually making the change explained things a bit better.

Note: you can make 120Hz HDR work up to 2432x1368 HiDPI (you can use BetterDisplay to unlock that resolution) which is slightly higher than the stock 2304x1296 mentioned here. Would have been better if the engineers pushed a bit harder and allow 2560x1440@120Hz HiDPI for HDR.

Thank you. That propobly explained why is many mouse on M1 start act erratic, windows cannot be resized, etc. Nice Job apple.

 

[dim_]

Went and updated my Sonoma installation to 14.3, still no change. Sort of expected, but still annoying.

By the way, do people here only experience this particular issue on M1 (either vanilla, Pro or Max), or is it also occurring for M2 owners?

 

[dim_]

When they fixed the M2 they also limited M1 (in the same move) - this indicates that probably the same engineer (or maybe a group of engineers) made the changes to both chip firmwares (the capabilities should depend on the rtOS - firmware - version running in a dedicated component of the Apple Silicon chip called "DCP").

I don't think the firmware is updated, only something in the display driver. Because if the firmware was permanently modified to no longer support those resolutions and refresh rates, it would no longer work under Ventura on the same machine. But it does.

In my view, it is just a software limitation for hardware "quirks", and they should limit it to the affected machines, in this case M2. Then M1 users will not have to suffer for M2's design faults.

 

[stevemr123]

Hi @dim_ - the firmware is loaded at boot time and is macOS version specific - each macOS version has its own build. It's not the usual firmware in the typical sense that it is somehow permanently stored inside the chip itself in some kind of eprom. It's actually a separate real time operating system (called rtOS) that runs inside this specific part of the Apple Silicon chip called DCP (Display Coprocessor probably) - a chip inside the chip. Each macOS has build has its own matching build for the DCP firmware (OS) and the two work together as the functionality is divided up between them - some stuff is handled by macOS, some by rtOS and they interface with each other in a specific way - neither of them can operate properly without the other. DCP handles display modes, all negotiations with displays (and among other things manages also the built-in DP2HDMI hardware for first gen Apple Silicon Macs) and also manages video memory bandwidth stuff (this is probably where the limitation of modes come).

The guys working on Asahi Linux posted a lot of stuff on how DCP works and how to interact with specific versions of the rtOS (based on their reverse engineering works) for those who are interested.

 

[dim_]

Ah yes, the good old method of saving on flash memory for firmware, by uploading firmware at boot time. Thanks for the explanation, it's clear to me now that Apple tried to fix an M2-specific HDR or refresh-rate issue, and their fix breaks perfectly working modes on M1. I am not really impressed by Sonoma's quality.

 

[sashavegas]

Ah yes, the good old method of saving on flash memory for firmware, by uploading firmware at boot time. Thanks for the explanation, it's clear to me now that Apple tried to fix an M2-specific HDR or refresh-rate issue, and their fix breaks perfectly working modes on M1. I am not really impressed by Sonoma's quality.

I am on M1 studio, and confirm that when i was reverting back to Monterey, but not last update (12.7.3), using previous verion, all problem is gone. So this flash is not permanet. But to be sure, i restored whole mac from AppleConfigurator. But if i updated to last version the problem comeback.

 

[dim_]

FWIW, I test-installed 14.4 beta 3 today, no change: HDR is still broken. I am now going to assume it stays broken for the life of Sonoma, and will likely never upgrade, at least on this M1 machine.