Acer Nitro XV273K: 144hz at 4K possible on M1 Pro / Max possible (two Displayport cables)?

[roach1245]

Hi all,

I got the Acer Nitro XV273K which can run at 4K 144hz 10-bit colors by connecting 2 Displayport cables to it.

I've tried a lot of things but my Macbook Pro (M1 Max, latest Monterey) always recognizes the monitor as 2 separate monitors when I connect 2 Displayport-to-USBC(or Thunberbolt) cables (I have tried many different cables from the office, always the same, also tried the single 8K cable mentioned below that should technically be able to do it by itself).

When I use one cable (e.g. a Displayport to USB C that is advertised as 8K cable) I can get:

- 120hz 4K with '8-bit colors' (or technically 'limited 10-bit chroma subsampling 422 compressed' from what I read). Not bad either but the colors are washed out, and would rather use it to its fullest potential, thus I'd want:

- Double DP 1.4 4k 144Hz 10-bit RGB uncompressed

I tried a lot of different things, such as:

- Holding alt option in System Preferences->Displays, showing all 'low resolution modes', but no luck
- Playing around with SwitchResX
- Figure out if there is a 'double DP' as input in monitor OSC settings (as in some Dell monitors), but there isn't
- Activated '4K 144hz mode' in monitor hardware menu, disabled freesync, disabled HDR, and so on. I think I've tried every combination of options available where the monitor hardware menu is concerned.

Would you have any clue? I am particularly curious why I get 2 separate monitors when connecting 2 cables - I have never seen the '144hz' option showing up anywhere on macOS.

Quotes I gathered from earlier (over 1 year ago) posts but not sure if yet fixed/updated by Apple:

"4K144 requires dual cable input but macOS has bad support for that (only works with displays that Apple tests)."

"It’s also probably not displaying in RGB colour format as mentioned in other posts most if not all displays are stuck YPBPR a big issue yet to be fixed by apple, most people don’t realize the loss of image quality but if you go into your settings on your monitor it will most likely indicate this."

Thank you!

 

[Amethyst1]

I am particularly curious why I get 2 separate monitors when connecting 2 cables [...]

That's expected.

The XV273K doesn't support DSC, so the only way for it to do "4K" resolution at 144 Hz and 10bpc RGB is to use two separate DisplayPort 1.4 inputs, each driving one half of the panel at 1920×2160 at 144 Hz. That is known as a "tiled display" or "dual-link SST".

Unfortunately, macOS needs to have explicit support for a given dual-link SST/tiled display, i.e. an .mtdd file that describes how the tiles are set up, in order to make it appear like a "normal" single-tiled display (like it does for e.g. a Dell UP2715K, HP Z27q or LG UltraFine 5K). It doesn't have an .mtdd file for the XV273K, which is why this doesn't work.

IIRC @joevt owns an XV273K and has done some testing with regards to the dual-link SST setup, so he may have better news than that.

 

[roach1245]

That's expected.

The XV273K doesn't support DSC, so the only way for it to do "4K" resolution at 144 Hz and 10bpc RGB is to use two separate DisplayPort 1.4 inputs, each driving one half of the panel at 1920×2160 at 144 Hz. That is known as a "tiled display" or "dual-link SST".

Unfortunately, macOS needs to have explicit support for a given dual-link SST/tiled display, i.e. an .mtdd file that describes how the tiles are set up, in order to make it appear like a "normal" single-tiled display (like it does for e.g. a Dell UP2715K, HP Z27q or LG UltraFine 5K). It doesn't have an .mtdd file for the XV273K, which is why this doesn't work.

IIRC @joevt owns an XV273K and has done some testing with regards to the dual-link SST setup, so he may have better news than that.

This is really insightful and useful, thanks a lot! This will help me along the way. Thanks @joevt in case you'd be able to help in any way with the setup!

I just googled .mttd files a bit but didn't get me that far... Is there a chance of this monitor being supported in this way in the future, also given that this monitor is already some years old?

 

[Amethyst1]

Is there a chance of this monitor being supported in this way in the future, also given that this monitor is already some years old?

Let's say it's not impossible... but I wouldn't bet too much on it to be honest.

 

[joevt]

I got the Acer Nitro XV273K which can run at 4K 144hz 10-bit colors by connecting 2 Displayport cables to it.

I've tried a lot of things but my Macbook Pro (M1 Max, latest Monterey) always recognizes the monitor as 2 separate monitors when I connect 2 Displayport-to-USBC(or Thunberbolt) cables (I have tried many different cables from the office, always the same, also tried the single 8K cable mentioned below that should technically be able to do it by itself).

When I use one cable (e.g. a Displayport to USB C that is advertised as 8K cable) I can get:

- 120hz 4K with '8-bit colors' (or technically 'limited 10-bit chroma subsampling 422 compressed' from what I read). Not bad either but the colors are washed out, and would rather use it to its fullest potential, thus I'd want:

- Double DP 1.4 4k 144Hz 10-bit RGB uncompressed

The XV273K uses pixel clock of 1066.51MHz for 4K 120Hz so it should definitely be able to do 8bpc. While 4K 120Hz 4:2:2 10bpc should be possible, it doesn't appear that macOS would let you choose that mode (on my Mac mini 2018 with W5700, there's no HDR mode for 120Hz but there could be if macOS would allow 4:2:2 10bpc).

I tried a lot of different things, such as:

- Holding alt option in System Preferences->Displays, showing all 'low resolution modes', but no luck
- Playing around with SwitchResX
- Figure out if there is a 'double DP' as input in monitor OSC settings (as in some Dell monitors), but there isn't
- Activated '4K 144hz mode' in monitor hardware menu, disabled freesync, disabled HDR, and so on. I think I've tried every combination of options available where the monitor hardware menu is concerned.

Would you have any clue? I am particularly curious why I get 2 separate monitors when connecting 2 cables - I have never seen the '144hz' option showing up anywhere on macOS.

144Hz only happens in macOS for this display when 4K-144Hz Mode is disabled...
Variable refresh rate works when FreeSync is enabled, but only for modes that can do 144Hz (such as 2560x1440).

Quotes I gathered from earlier (over 1 year ago) posts but not sure if yet fixed/updated by Apple:

"4K144 requires dual cable input but macOS has bad support for that (only works with displays that Apple tests)."

True. macOS bad.

"It’s also probably not displaying in RGB colour format as mentioned in other posts most if not all displays are stuck YPBPR a big issue yet to be fixed by apple, most people don’t realize the loss of image quality but if you go into your settings on your monitor it will most likely indicate this."

DisplayPort usually does RGB. This can easily be detected on Intel Macs but I don't know how to check that on M1 Macs. Some monitors with onscreen menus will tell you when they are using RGB or YCbCr but I don't see that on the XV273K.

That's expected.

The XV273K doesn't support DSC, so the only way for it to do "4K" resolution at 144 Hz and 10bpc RGB is to use two separate DisplayPort 1.4 inputs, each driving one half of the panel at 1920×2160 at 144 Hz. That is known as a "tiled display" or "dual-link SST".

Unfortunately, macOS needs to have explicit support for a given dual-link SST/tiled display, i.e. an .mtdd file that describes how the tiles are set up, in order to make it appear like a "normal" single-tiled display (like it does for e.g. a Dell UP2715K, HP Z27q or LG UltraFine 5K). It doesn't have an .mtdd file for the XV273K, which is why this doesn't work.

IIRC @joevt owns an XV273K and has done some testing with regards to the dual-link SST setup, so he may have better news than that.

I tried making an mtdd file for the XV273K and I put it in the /var/db/displaypolicyd/ folder (name "Display-ACR-6b1.mtdd") as described at https://forums.macrumors.com/threads/studio-display-natural-resolution.2338616/post-30974390 but the /var/log/displaypolicy/displaypolicyd.72:0:0.log says "WARNING: lanes 4 @ HBR3 can not support multi-link display" which is strange since the XDR uses dual HBR3x4.

I don't know if M1 Macs use displaypolicyd....

 

[roach1245]

Thanks a lot for the info @joevt ! I am going to test out that mtdd file and see if it works on the M1......

 

[stuk]

Did you manage to make any progress here? Curious as I'm considering buying this monitor

 

[joevt]

Did you manage to make any progress here? Curious as I'm considering buying this monitor

Still a work in progress. Ventura added support for dual cable 8K60 mode on the Dell UP3218K for some subset of Mac Pro 2019 computers. I made a Lilu/WhateverGreen patch (installed by OpenCore) to make it work on all Macs.

Something is still disabling dual cable mode for the XV273K. My next trick is to try to add a kind of EDID override (lower level than the Displays Overrides kind) that will make macOS think my XV273K is Dell UP3218K.

Maybe you should consider a newer display that uses DSC instead of dual cable. You need a GPU that supports DSC. macOS might not enable DSC by default unless maybe you're running Catalina.