MP All Models SOLVED: 8k Displays Running on Mac Pro? Any? What Video cards would work that support 8k HDMI 2.1/Displayport 1.4/2.0 displays on Mac Pro? YES you can

[ZombiePhysicist]

There was an earlier post from you which listed more cables and adapters.
https://forums.macrumors.com/thread...-on-mac-pro-yes-you-can.2309750/post-30712378

You've only shown info for this cable:
https://www.amazon.com/dp/B0994FPCMD CableDeconn DisplayPort 1.4 to HDMI 2.1 8K Cable

We do not have any info (AGDCDiagnose and tests) from you about these:
https://www.amazon.com/dp/B08XFYHFCK CableMatters 101101 8K Mini DP to HDMI Adapter
https://www.amazon.com/dp/B094XDDRL6 CableMatters 101109 8K Mini DP to HDMI Cable
https://www.amazon.com/dp/B08QDV5H4M CableMatters 201362 USB C to 8K HDMI Cable
https://www.amazon.com/dp/B08Y246V8X Sabrent USB Type-C to HDMI 2.1 Adapter

Ah, I see what youre asking for. Sorry, didnt understand. Ok, will try to get all the AGD reports on that in a bit.

Question about the last test in that post:
this one: "6900XT | USB-c port 4 via DP adapter | TVHDMI2.1 port 1 | FakeAlmost8k | MiniDP1.4 to HDMI2.1 Cable"
How did you connect Mini DP to the USB-C to DP adapter?
You'll need a DisplayPort (male) to Mini-DisplayPort (female) adapter to test your Mini DP adapters and cables with the 6900XT
or a USB-C to Mini-DisplayPort (female) adapter.

So what you quoted there was, I think, a typo that I corrected a while back, not sure why it's still showing you that. But this is what I corrected it to:

With that last one, the adapter has a male USBc that plugs into the female USBc port of the 6900. It has a female HDMI port. So then a regular male to male HDMI cable plugs one end into the USBc/hdmi adapter, and the other end into the TV.

I would like you to run the utility to get the firmware version from the cable and extract the firmware. You don't need to modify the firmware if you don't want to. I am wondering why the cable doesn't show support for DSC in the AGDCDiagnose output.

Ok, I got it and this is what it returns:

And this is what windows shows is the mode. Interestingly windows maxes out at 30hz with that cable whereas macOS uses 60hz setting. I imagine the cable might be pumping out less color information to make the 60hz work on macOS.

Here are some other options:
https://www.amazon.com/dp/B08MSWMXT4 CableMatters 201388 USB C to 8K HDMI Adapter (uses VMM6100)
https://www.amazon.com/dp/B08BX49V5V Club-3D CAC-1085 DisplayPort 1.4 to HDMI 4K120 Adapter (uses Realtek RTD2173)
https://www.amazon.com/dp/B092RD7MQR Club 3D CAC-1586 USB Type-C to HDMI 4K 120Hz Adapter

So I have that Cablematters adapter that looks like this:

I used it in one of the earlier tests and will run the diagnostic report on it for you. But the cable that I'm using currently that works with 8k is not that adapter, it is this CableDeconn one:

The firmware utility I ran was on the CableDeconn cable and if I understand and read it correctly, it showed version 6.03.146

 

[joevt]

Ah, I see what youre asking for. Sorry, didnt understand. Ok, will try to get all the AGD reports on that in a bit.

Would be much appreciated. I want to get into some DSC experiments so we need an adapter that reports DSC support.
I don't have an 8K display, so on my end I am looking at Lilu/WhateverGreen combination to see if it can do some DSC enablement. Specifically, we'll want to see if we can force DSC @ 8bpp instead of the usual 12bpp that macOS uses. Also, since you have an 8K display, it might be interesting if macOS can be forced to use an x3 HiDPI mode so you can get a nice 2560x1440 HiDPI mode that uses 8K instead of 5K.

So what you quoted there was, I think, a typo that I corrected a while back, not sure why it's still showing you that. But this is what I corrected it to:
View attachment 1936142

With that last one, the adapter has a male USBc that plugs into the female USBc port of the 6900. It has a female HDMI port. So then a regular male to male HDMI cable plugs one end into the USBc/hdmi adapter, and the other end into the TV.

Except in your picture of the table, you show the last row is USB-C male to DisplayPort female and the cable is the Deconn DisplayPort 1.4 to HDMI2.1 Cable.

Ok, I got it and this is what it returns:

Instead of a screenshot, click the "Dump all" button to get all the info. I am looking for what it says about the connection between the HDMI port and the display.
I've attached some examples for other adapters.
Another interesting button is "Debug message". It saves a log of messages from the adapter. I guess try running it just after the display is registered and running at the desired resolution and refresh rate?
You can get a slightly newer version of the VmmDpTool from the Microsoft Store. Some of the attached examples came from VmmUpdater which is also from the Microsoft Store.

And this is what windows shows is the mode. Interestingly windows maxes out at 30hz with that cable whereas macOS uses 60hz setting. I imagine the cable might be pumping out less color information to make the 60hz work on macOS.

Remember that the Deconn cable removes the 8K50 and 8K60 modes. You'll need to re-add them. Download Custom Resolution Utility (CRU) from https://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU
Get the EDID for the TV using a connection from the HDMI port of the 6900XT using CRU and save it to a file and/or copy.
Then, with the connection using the Deconn cable, override the EDID with the EDID from the HDMI port by clicking paste. You can change the name of the display in the EDID to something like "Q900port1" or whatever port you connect the display to so you can know when the EDID is working (click "Edit..." and enter up to 13 characters for the name). You can do the same for the EDID of the HDMI port. EDID overrides in Windows are per <GPU port & display vendor & display product>. On macOS, the EDID overrides are <per display vendor & display product> or <display vendor & display week of manufacture>. So in Windows, you need to override the EDID for all the ports that you're going to connect the adapter to (or just remember to use the same port all the time).

So I have that Cablematters adapter that looks like this:
View attachment 1936132

I used it in one of the earlier tests and will run the diagnostic report on it for you. But the cable that I'm using currently that works with 8k is not that adapter, it is this CableDeconn one:
View attachment 1936131

That Cable Matters 201388 one should have DSC support. You'll want to use the firmware updater to verify the firmware version. And maybe update it. Get an AGDCDiagnose before and after update. Try and see if Windows will use DSC to get 8K60.

The firmware utility I ran was on the CableDeconn cable and if I understand and read it correctly, it showed version 6.03.146

That is a newer firmware than I've seen for the Cable Matters 201388 adapter, but it doesn't have DSC enabled so it's not useful for further testing until you try updating its firmware.

 

[PieroPontra]

I got an 8K Samsung TV too and linking an HDMI 2.1 cable from HDMI 2.1 GPU port straight to TV's HDMI port doesn't seem to work as per your method, maybe I need to pass from a DP port to trick it? I also experience dithering even with Game Mode on. On Windows I got 8K 60Hz RGB 10 bit with the same linking and the only thing which makes dithering to disappear is switching to Game Mode, precisely... it's the Freesync VRR which does the dithering trick since if I disable it then dither comes back. Should I buy that Cabledeconn DP 1.4 ---> HDMI 2.1 cable?

Please note that I'm on an hackintosh, so I'm pretty familiar with whatevergreen and related. Feel free to use me as a test guy. MacPro7,1 SMBIOS !

Do you think macOS will ever support 2.1? I'm pretty scared... You know...

https://hdfury.com/product/dr-hdmi-8k/ <---- Would this do some kind of black magic?

 

[joevt]

I got an 8K Samsung TV too and linking an HDMI 2.1 cable from HDMI 2.1 GPU port straight to TV's HDMI port doesn't seem to work as per your method, maybe I need to pass from a DP port to trick it?

The HDMI port is limited to HDMI 2.0 bandwidth in macOS so the successful tests that achieved 8K60 8bpc 4:2:0 were done with the Deconn cable containing the Synaptics VMM6100 that has no DSC support.

Should I buy that Cabledeconn DP 1.4 ---> HDMI 2.1 cable?

Only if you want to try to reproduce the 8K60 8bpc 4:2:0 mode. A DisplayPort adapter with DSC is needed to get 8K60 4:4:4 10bpc.

I also experience dithering even with Game Mode on. On Windows I got 8K 60Hz RGB 10 bit with the same linking and the only thing which makes dithering to disappear is switching to Game Mode, precisely... it's the Freesync VRR which does the dithering trick since if I disable it then dither comes back.

This video explains what options should be turned off for best viewing of movies:

I suppose Game mode does some of them? Does your Samsung have filmmaker mode?

Please note that I'm on an hackintosh, so I'm pretty familiar with whatevergreen and related. Feel free to use me as a test guy. MacPro7,1 SMBIOS !

I think Lilu/WhateverGreen has user mode patching for Catalina but I need to do some more tests. This would only be useful for 5000 series cards. 6000 series cards need Big Sur or Monterey. User mode patching isn't working in Monterey yet. I haven't tested Big Sur yet. Kext patching should work in any macOS version. We just need to find a patch that is useful. I have noticed that macOS AMD drivers have parts of code seen in Linux drivers so that may be an interesting place to look. Does AMD open source Linux drivers support HDMI 2.1?

Do you think macOS will ever support 2.1? I'm pretty scared... You know...

Maybe macOS will support it one day - maybe it will be only supported on Apple Silicon...

https://hdfury.com/product/dr-hdmi-8k/ <---- Would this do some kind of black magic?

It makes it easier to override the EDID but we can already do that. I don't think any of its other features are useful in this situation.

 

[PieroPontra]

The HDMI port is limited to HDMI 2.0 bandwidth in macOS so the successful tests that achieved 8K60 8bpc 4:2:0 were done with the Deconn cable containing the Synaptics VMM6100 that has no DSC support.


Only if you want to try to reproduce the 8K60 8bpc 4:2:0 mode. A DisplayPort adapter with DSC is needed to get 8K60 4:4:4 10bpc.


This video explains what options should be turned off for best viewing of movies:

I suppose Game mode does some of them? Does your Samsung have filmmaker mode?


I think Lilu/WhateverGreen has user mode patching for Catalina but I need to do some more tests. This would only be useful for 5000 series cards. 6000 series cards need Big Sur or Monterey. User mode patching isn't working in Monterey yet. I haven't tested Big Sur yet. Kext patching should work in any macOS version. We just need to find a patch that is useful. I have noticed that macOS AMD drivers have parts of code seen in Linux drivers so that may be an interesting place to look. Does AMD open source Linux drivers support HDMI 2.1?


Maybe macOS will support it one day - maybe it will be only supported on Apple Silicon...


It makes it easier to override the EDID but we can already do that. I don't think any of its other features are useful in this situation.

Yes, I'm interested in 8K 60Hz 4:4:4 / RGB so if you can steer me to an adapter / cable which should do the job I'll buy all of them and then return what doesn't work. I'm in Italy but Amazon IT has pretty much all Amazon US has.

In Game Mode all postprocessing is disabled by default, so I don't think dithering is caused by it. I think the TV disables it when a VRR / Freesync is engadged. Please do not 2 things:

1. Dither goes away in Windows only when VRR is engaged, in windows it shows me Freesync Premium Pro as ON and dither disappears

2. macOS begun supporting Adaptive Sync (Apple's name for VRR) with Monterey 12.1 but only via the DisplayPorts, that's why I think @ZombiePhysicist was able to engage it, since he used a DisplayPort. Obviously an his focus on this would be helpful.

 

[ZombiePhysicist]

Sorry all, will have to take a break for a little while with the tests. Had to move the TV onto my credenza as we have holiday/family coming to the house and it needed tidying up. And none of the cables reach. I'm going to be ordering what I need to mount this right up on my desk in the mean time, so hopefully that doesnt take to long too get mounted and I can get back to testing.

 

[ZombiePhysicist]

Yes, I'm interested in 8K 60Hz 4:4:4 / RGB so if you can steer me to an adapter / cable which should do the job I'll buy all of them and then return what doesn't work. I'm in Italy but Amazon IT has pretty much all Amazon US has.

In Game Mode all postprocessing is disabled by default, so I don't think dithering is caused by it. I think the TV disables it when a VRR / Freesync is engadged. Please do not 2 things:

1. Dither goes away in Windows only when VRR is engaged, in windows it shows me Freesync Premium Pro as ON and dither disappears

2. macOS begun supporting Adaptive Sync (Apple's name for VRR) with Monterey 12.1 but only via the DisplayPorts, that's why I think @ZombiePhysicist was able to engage it, since he used a DisplayPort. Obviously an his focus on this would be helpful.

The regular HDMI2.1 cable wont work in macOS (although it works just fine in windows and you get full 8k@60hz, I think at 4:4:4).

Yea, I couldn't get 8k@60 with 4:4:4 on macOS even with the Deconn. At least not yet.

With the Deconn it works in macOS at 8k@60hz at 4:2:0 I think? Frankly it looks great, so I'm totally fine with it for now. Of course, hoping we can get it to eventually work at full 4:4:4 8k@60hz with some of the other adapters I got, but we're still experimenting with that.

 

[joevt]

With the Deconn it works in macOS at 8k@60hz at 4:2:0 I think? Frankly it looks great, so I'm totally fine with it for now. Of course, hoping we can get it to eventually work at full 4:4:4 8k@60hz with some of the other adapters I got, but we're still experimenting with that.

4:2:0 is fine for grayscale stuff (it has full grayscale resolution) but for different colors next to each other, it has only half the resolution. I suppose text will look best if it's grayscale and the OS doesn't try to do sub pixel antialiasing using different colors. Read about chroma sub sampling artifacts at https://www.rtings.com/tv/learn/chroma-subsampling and check the test pattern - the red/blue text on blue/red background looks terrible using 4:2:0.

DSC compression is smarter than 4:2:0 in regards to what information it throws away. It uses more pixels at once to decide what to do instead of just the 2x2 pixels that 4:2:0 uses.

So first we need to find a DisplayPort adapter that can do 8k60 4:4:4 10bpc in Windows. That will require an adapter with DSC. Then we need to make it work in macOS. For 2376MHz we need the DSC to do 10+14/16 bpp or better (DSC compression is measured in sixteenths of a pixel - macOS uses 192 for the 6K60 XDR - we'll need 174 for 8K60).

 

[ZombiePhysicist]

4:2:0 is fine for grayscale stuff (it has full grayscale resolution) but for different colors next to each other, it has only half the resolution. I suppose text will look best if it's grayscale and the OS doesn't try to do sub pixel antialiasing using different colors. Read about chroma sub sampling artifacts at https://www.rtings.com/tv/learn/chroma-subsampling and check the test pattern - the red/blue text on blue/red background looks terrible using 4:2:0.

DSC compression is smarter than 4:2:0 in regards to what information it throws away. It uses more pixels at once to decide what to do instead of just the 2x2 pixels that 4:2:0 uses.

So first we need to find a DisplayPort adapter that can do 8k60 4:4:4 10bpc in Windows. That will require an adapter with DSC. Then we need to make it work in macOS. For 2376MHz we need the DSC to do 10+14/16 bpp or better (DSC compression is measured in sixteenths of a pixel - macOS uses 192 for the 6K60 XDR - we'll need 174 for 8K60).

If youre a color pro, no doubt what you say is true. But honestly, the screen looked pretty ok. I'm sure it would look better. Most of my work is some light coding, word processing, and reviewing technical documents. So color fidelity isnt really important. Youtube videos look pretty great. But yea, I do see some color artifacting, but not terrible. If you at all work with lots of serious color and stuff, I think youre right.

Hopefully we can get an even better result. But for now, this is enough for me to keep this display and it will be super usable for me, and we can work more on it.

And happy happy new year @joevt!

 

[PieroPontra]

4:2:0 is fine for grayscale stuff (it has full grayscale resolution) but for different colors next to each other, it has only half the resolution. I suppose text will look best if it's grayscale and the OS doesn't try to do sub pixel antialiasing using different colors. Read about chroma sub sampling artifacts at https://www.rtings.com/tv/learn/chroma-subsampling and check the test pattern - the red/blue text on blue/red background looks terrible using 4:2:0.

DSC compression is smarter than 4:2:0 in regards to what information it throws away. It uses more pixels at once to decide what to do instead of just the 2x2 pixels that 4:2:0 uses.

So first we need to find a DisplayPort adapter that can do 8k60 4:4:4 10bpc in Windows. That will require an adapter with DSC. Then we need to make it work in macOS. For 2376MHz we need the DSC to do 10+14/16 bpp or better (DSC compression is measured in sixteenths of a pixel - macOS uses 192 for the 6K60 XDR - we'll need 174 for 8K60).

What about this one? It’s Usb-c > HDMI but clearly states 8K 60 with DSC

Sabrent - Adattatore USB tipo C a HDMI 2.1, 8 K/60 Hz e 4 K/120 Hz con funzione DSC, risoluzione 8 K/30 Hz e 4 K senza DSC, compatibile con Thunderbolt 3 (DA-UCH8) https://www.amazon.it/dp/B08Y246V8X...t_i_SRPJ7BE6H2A9CCBVADEV?_encoding=UTF8&psc=1

 

[PieroPontra]

If youre a color pro, no doubt what you say is true. But honestly, the screen looked pretty ok. I'm sure it would look better. Most of my work is some light coding, word processing, and reviewing technical documents. So color fidelity isnt really important. Youtube videos look pretty great. But yea, I do see some color artifacting, but not terrible. If you at all work with lots of serious color and stuff, I think youre right.

Hopefully we can get an even better result. But for now, this is enough for me to keep this display and it will be super usable for me, and we can work more on it.

And happy happy new year @joevt!

Could you please verify if some sort of VRR / FreeSync is engaged on yours? I'm asking because as I stated previously, on my QN700A (European 55" version of a QN800A) the only thing which disables dither in Win 11 is activating VRR otherwise the image is completely dithered and rubbish, even at 8K 60Hz RGB. You should check System Preferences - Display Settings (where macos allows you to modify refresh rate basically). since 12.1 macos supports Adaptive Sync only via DisplayPort, they really dislike HDMI ;-)

Happy new year everyone

 

[joevt]

We just need to find a patch that is useful. I have noticed that macOS AMD drivers have parts of code seen in Linux drivers so that may be an interesting place to look. Does AMD open source Linux drivers support HDMI 2.1?

My first realization that macOS AMD drivers has linux AMD driver code is from the discussion at https://github.com/kingo132/a51m-r2-5700m-hackintosh/blob/main/fix_navi10_4k_120hz.md which was regarding the X6000Framebuffer driver in Big Sur. Monterey is mostly the same, but the names of the AMD linux functions are stripped.

Looking at the Linux code, it appears to be missing some HDMI 2.1 stuff. Googling for HDMI 2.1 and linux finds results that suggest that HDMI licensing won't allow open source drivers to have HDMI 2.1 stuff? In particular, the dc_link_validate_mode_timing function doesn't have an option for FRL: there's just one option for DP which calls function dp_validate_mode_timing . But what's interesting is that the macOS driver does have an option for FRL, which calls a function named frl_validate_mode_timing . I think this bit of code is for DisplayPort adapters? I don't know if it applies to the HDMI 2.1 port. I guess we could use Lilu/Whatevergreen patches to log information from these functions - those are the easiest kind of patches.

 

[PieroPontra]

My first realization that macOS AMD drivers has linux AMD driver code is from the discussion at https://github.com/kingo132/a51m-r2-5700m-hackintosh/blob/main/fix_navi10_4k_120hz.md which was regarding the X6000Framebuffer driver in Big Sur. Monterey is mostly the same, but the names of the AMD linux functions are stripped.

Looking at the Linux code, it appears to be missing some HDMI 2.1 stuff. Googling for HDMI 2.1 and linux finds results that suggest that HDMI licensing won't allow open source drivers to have HDMI 2.1 stuff? In particular, the dc_link_validate_mode_timing function doesn't have an option for FRL: there's just one option for DP which calls function dp_validate_mode_timing . But what's interesting is that the macOS driver does have an option for FRL, which calls a function named frl_validate_mode_timing . I think this bit of code is for DisplayPort adapters? I don't know if it applies to the HDMI 2.1 port. I guess we could use Lilu/Whatevergreen patches to log information from these functions - those are the easiest kind of patches.

I don't know how to handle this kind of stuff, but if you want me to try some kind of kext... here I am.

 

[joevt]

I don't know how to handle this kind of stuff, but if you want me to try some kind of kext... here I am.

It will take a while to come up with anything. You could provide some info in the mean time.

Check the instructions for getting a log when a display is connected #140
1) With the display unconnected, get the start time, connect the display, wait for it to register, get the end time, save the log to a file.
2) Grab the EDID from the HDMI port of the GPU using AGDCDiagnose.

Get a DislayPort 1.4 to HDMI 2.1 adapter like the Cable Matters 201388 or the CAC-1085. If the former, check the firmware and maybe update it. If the latter, e-mail Club-3d for a firmware updater just in case you get an older one.
Do the same steps #1, #2 except connect the display using the adapter this time.
Check if the adapter gives 8K60 RGB in Windows.

 

[PieroPontra]

It will take a while to come up with anything. You could provide some info in the mean time.

Check the instructions for getting a log when a display is connected #140
1) With the display unconnected, get the start time, connect the display, wait for it to register, get the end time, save the log to a file.
2) Grab the EDID from the HDMI port of the GPU using AGDCDiagnose.

Get a DislayPort 1.4 to HDMI 2.1 adapter like the Cable Matters 201388 or the CAC-1085. If the former, check the firmware and maybe update it. If the latter, e-mail Club-3d for a firmware updater just in case you get an older one.
Do the same steps #1, #2 except connect the display using the adapter this time.
Check if the adapter gives 8K60 RGB in Windows.

please read my previous two posts which took a while to get approved by moderators, especially the one regarding the Sabrent adapter, then I'd buy the one adapter which gives us the most probabilities to work with DSC. I think DSC compatibility is what we need to get 8K 60Hz Full RGB.

 

[hardwickj]

please read my previous two posts which took a while to get approved by moderators, especially the one regarding the Sabrent adapter, then I'd buy the one adapter which gives us the most probabilities to work with DSC. I think DSC compatibility is what we need to get 8K 60Hz Full RGB.

@PieroPontra My understanding is that won't work since MacOS would see it as an HDMI adapter, and MacOS's drivers are limited to HDMI 2.0. I'm guessing what you'd need is a USB-C to DisplayPort 1.4 adapter, then a DisplayPort 1.4 to HDMI 2.1 adapter/cable, since (presumably) the only way to get DSC to work in MacOS is via DisplayPort 1.4.

Perhaps something like this combo?

1. CalDigit USB-C to DisplayPort 1.4 Adapter
2. UPTab DisplayPort 1.4 to HDMI 2.1 Active Adapter

 

[joevt]

@PieroPontra My understanding is that won't work since MacOS would see it as an HDMI adapter, and MacOS's drivers are limited to HDMI 2.0. I'm guessing what you'd need is a USB-C to DisplayPort 1.4 adapter, then a DisplayPort 1.4 to HDMI 2.1 adapter/cable, since (presumably) the only way to get DSC to work in MacOS is via DisplayPort 1.4.

Perhaps something like this combo?

1. CalDigit USB-C to DisplayPort 1.4 Adapter
2. UPTab DisplayPort 1.4 to HDMI 2.1 Active Adapter

There won't be any difference between USB-C or DisplayPort when it comes to HDMI adapters since USB-C uses DisplayPort.
Anyway, we already know that Apple doesn't limit HDMI 2.1 adapters to HDMI 2.0 since we got 8K60 4:2:0 8bpc to work which requires more bandwidth than HDMI 2.0.

 

[PieroPontra]

Yes, so should I buy the Sabrent adapter? Didn't @ZombiePhysicist already bought and tried it? I'm asking since it's the only one showing off a DSC compatibility.

 

[joevt]

Yes, so should I buy the Sabrent adapter? Didn't @ZombiePhysicist already bought and tried it? I'm asking since it's the only one showing off a DSC compatibility.

@ZombiePhysicist did try it #89 but did not do all the tests that he did with the Deconn cable/adapter so we have next to no info about it.

Buy any adapter you want to test but assume none of them will work or at least that none will do better than 8K60 8bpc 4:2:0. Then we do experiments to try to get beyond that or to get more info.

 

[Arvine]

Yes, so should I buy the Sabrent adapter? Didn't @ZombiePhysicist already bought and tried it? I'm asking since it's the only one showing off a DSC compatibility.

The Club 3D Cac-1085 DP to HDMI 2.1 should have DSC 1.2.

 

[PieroPontra]

@ZombiePhysicist did try it #89 but did not do all the tests that he did with the Deconn cable/adapter so we have next to no info about it.

Buy any adapter you want to test but assume none of them will work or at least that none will do better than 8K60 8bpc 4:2:0. Then we do experiments to try to get beyond that or to get more info.

Checking a bunch of reviews on Amazon it's pretty clear people are just getting 8K 60Hz RGB from Sabrent adapter + HDMI 48gbps cable so I bought one, at least we know it should work and I got Win 11 + macos 12.1 installed on the same machine to test it out. I also googled a bit and should be confirmed that usb-c port on rdna 2 cards support DP Alt Mode 1.4 + DSC. I'll let you know when it arrives!!

 

[joevt]

The following command may change DSC bpp from 12 to 8 which is necessary for some timings to allow 4:4:4 (such as 8K60 HDMI from DisplayPort 1.4)
sudo defaults write /Library/Preferences/com.apple.CoreDisplay dscTargetBPP -int 8

to undo the setting:
sudo defaults delete /Library/Preferences/com.apple.CoreDisplay dscTargetBPP

A restart may be required for the setting to take affect. You can test that be checking the output from the log show test I described before.

This was from looking at CoreDisplay code in Catalina 10.15.7. I haven't tested it. I haven't looked at the Monterey CoreDisplay code. I don't think M1 Macs use CoreDisplay code?

Actually, DisplayPort 1.4 should be able to do 8K60 HDMI with 10 bpp but the Samsung's EDID seems to indicate that its HDMI 2.1 inputs are limited to FRL 6Gbps (21.33 Gbps) when using DSC so 8bpp would be required for the HDMI mode on the Samsung.

But then again, @ZombiePhysicist used a non-HDMI timing of 2090MHz which should have worked with DSC @ 12bpp (but he hasn't gotten around to trying 2090MHz with an adapter that supports DSC). I don't know if the adapters recompress the DSC - if not, then 10bpp would be required for the 2090MHz mode on the Samsung.

 

[PieroPontra]

The following command may change DSC bpp from 12 to 8 which is necessary for some timings to allow 4:4:4 (such as 8K60 HDMI from DisplayPort 1.4)
sudo defaults write /Library/Preferences/com.apple.CoreDisplay dscTargetBPP -int 8

to undo the setting:
sudo defaults delete /Library/Preferences/com.apple.CoreDisplay dscTargetBPP

A restart may be required for the setting to take affect. You can test that be checking the output from the log show test I described before.

This was from looking at CoreDisplay code in Catalina 10.15.7. I haven't tested it. I haven't looked at the Monterey CoreDisplay code. I don't think M1 Macs use CoreDisplay code?

Actually, DisplayPort 1.4 should be able to do 8K60 HDMI with 10 bpp but the Samsung's EDID seems to indicate that its HDMI 2.1 inputs are limited to FRL 6Gbps (21.33 Gbps) when using DSC so 8bpp would be required for the HDMI mode on the Samsung.

But then again, @ZombiePhysicist used a non-HDMI timing of 2090MHz which should have worked with DSC @ 12bpp (but he hasn't gotten around to trying 2090MHz with an adapter that supports DSC). I don't know if the adapters recompress the DSC - if not, then 10bpp would be required for the 2090MHz mode on the Samsung.

Yeah, another thing to try when the adapter will be in my hands. Noted! Can't wait ;-)

 

[PieroPontra]

Just to let you know guys that I'm not disappeared, I'm just waiting for the Sabren adapter to be delivered since Epiphany is a pretty important holiday in Italy and logistics is stopped. Well... monday would be the day, happy weekend!!

 

[ZombiePhysicist]

Ok so got some extension cables to do some more testing until I get my final mount in place.

So some interesting results as I'm now testing with the Sabrent USBc adapter and a new 16.4 foot version of this cable.

So first thing that is interesting is that the regular 4k (3840x2160@60hz) does not seem to initially work with this setup, however, setting it to 4096x2160@60hz does work, and then setting back to the 3840 mode then does work. Strange.

The 8k non scaled versions of resolution do not show up at all:

Also HDR does not show up as an option, even in 4k in the displays panel. I also tried both 5k resolutions but the TV wouldn't work with them.

So the results from AGC dump are attached. I'm going to do the same thing with the Cablematters adapter.

I wish I knew what to look for in that AGC dump and how to translate that to what I need to enter in the custom resolutions tab of SwitchResX to see if we can get 8k via this route (particularly if we can enable DSC compression), but will need your help to figure that out. Thanks!

That said, snooping at the output I did notice it showed DSC seems to be enabled?

Display Path (Active) FB0 DICT 21​

surface_address 0x700000​

surface_bytes 33423360​

bytes_per_row 15360​

bits_per_pixel 32​

bits_per_component 10​

Is Connected YES​

Is Online YES​

Is SW Scaled NO​

WSAA State "Accelerated"​

SW Src Viewport 3840x2160 @ {0,0}​

SW Dst Viewport 3840x2160 @ {0,0}​

Stream Count 1​

FB Index 0​

Group Index 0​

Mode Id 0x80007000​

Depth Index 2​

HW Src Viewport 3840x2160 @ {0,0}​

HW Dst Viewport 3840x2160 @ {0,0}​

Underscan 100 % - {75:100}​

​

Stream@0 FB0 DICT 13​

Stream ID 0​

Is Enabled YES​

Is DPMS Off NO​

Change Flags 0​

Option Flags 0​

Sink Address 2.0​

HW Src Viewport 3840x2160 @ {0,0}​

HW Dst Viewport 3840x2160 @ {0,0}​

​

Timing FB0 DICT 24​

Display Mode 80007000​

Refresh Rate (Calculated) 60 Hz​

Refresh Rate (Stored) 0.0 Hz​

Window (Active) 3840 x 2160​

Window (Scaled) 0 x 0​

Scaled Inset 0 x 0​

Pixel Clock 594000000 Hz​

Scaler Flags 0​

Signal Config 0​

Blanking 560 x 90​

Border {left,right} {0, 0}​

Border {top,bottom} {0, 0}​

Sync Offset (h, v) 176 x 8​

Sync Pulse Width (h, v) 88, 10​

Sync Config (h, v) + x +​

Num Links 2​

VB Extension 0​

OUTPUT: Pixel Encoding 8 (YCbCr420)​

OUTPUT: Bits Per Color Component 4 (10 bpc)​

OUTPUT: Colorimetry 128 (BT.709)​

OUTPUT: Dynamic Range 1 (SDR)​

DSC: Num Slices 0 x 0​

DSC: Slice Dimensions 0 x 0​

DSC: Compressed BPP 0 bits, (0 bits*16) )​