4K@144Hz no longer working after update

[red_epicness]

Hello,

I have just updated to Big Sur and the os will no longer output 4K @ 144Hz to my monitor. First my setup:

Base MacBook Pro 15" 2018
Akitio Node Pro enclosure
RX 5700 XRT eGPU
LG 27GN950-B (Capable of 30-bit colors, HDR, 4K, 144Hz)

To support these features both the display and GPU must support Display Stream Compression (which they obviously do)

Before updating, every feature of the monitor worked out of the box I only had to use option + Scaled in System Preferences to select the highest refresh rate. But after updating to Big Sur the monitor is now capped at either 4K @ 60Hz (with HDR) or 4K @ 95Hz (without HDR). another option appears when I manually toggle my monitor to normal 1.4 DisplayPort mode (as opposed to using DSC), which is 4K @ 120Hz without HDR. I am at a loss here as I have tried rebooting/unplugging all of the devices and connecting them in different order without any success. It simply looks as if Display Stream Compression is not turning on, which corresponds with the limits on the resolutions I can see. But I find it hard to believe DSC would be broken as Apple's own monitors use it to pass enough data to drive them using a single cable.

Does anyone have any other ideas on how to troubleshoot this? Would it be worth installing the 11.0.2 RC if it fixes the issue? Any opinion as tho what might be happening here is welcome.

System Information output:

Radeon RX 5700 XT:

Chipset Model: Radeon RX 5700 XT
Type: External GPU
Bus: PCIe
PCIe Lane Width: x4
VRAM (Total): 8 GB
Vendor: AMD (0x1002)
Device ID: 0x731f
Revision ID: 0x00c1
ROM Revision:
Automatic Graphics Switching: Supported
gMux Version: 5.0.0
Metal Family: Supported, Metal GPUFamily macOS 2
GPU is Removable: Yes

Displays:
27GN950:
Resolution: 7680x4320 (4320p/8K UHD 2 - 8K Ultra High Definition)
UI Looks like: 3840 x 2160 @ 95Hz
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Display Serial Number: ---
Main Display: Yes
Mirror: Off
Online: Yes
Rotation: Supported
Automatically Adjust Brightness: Yes
Connection Type: Thunderbolt/DisplayPort



Thanks,
Red_Epicness

 

[red_epicness]

I am attaching the EDID data as reported by SwitchResX if it helps anyone...

 

[April12]

I am having the same issue

 

[royalty12]

did you figure out a solution?

 

[red_epicness]

I have not yet found a solution. I installed 11.1 Beta, but the issue remains. Submit a feedback to Apple using the Feedback Assistant if you are able, every reports helps I hope.

 

[z3sty]

I have been getting this same problem ever since upgrading to 11.1. Used to be able to get 3440x1440 running @ 144hz but now its capped at 60hz and the option to change it is greyed out. Also whenever I restart my monitor goes to 800x640 and I have to manually change it to 3440x1440. I have a base model 16"

 

[penny00]

There is no solution, Apple broke DSC for AMD GPUs in Big Sur.

4k@144Hz no longer available after upgrade to Big Sur

Hello, I have just updated to Big Sur and the os will no longer output 4K @ 144Hz to my monitor. First my setup: Base 2018 15" MacBook Pro Akitio...

egpu.io

https://www.reddit.com/r/Monitors/comments/k3l24r/_/gejl7w5 https://www.reddit.com/r/mac/comments/jcjhpa

 

[aednichols]

Data point:

I have the LG 27GN950 and an M1 MacBook Air and DSC works in Big Sur.

So it seems that Apple does intend to keep supporting DSC/144Hz in Big Sur, there's just a bug with AMD GPUs. This should be mildly good news for those waiting for a fix.

 

[turbineseaplane]

Any updates on this?

@red_epicness

Would I be right in thinking that, when working properly, you can get the smooth hi refresh responsiveness that's on the latest iPads with ProMotion?

 

[aednichols]

Any updates on this?

@red_epicness

Would I be right in thinking that, when working properly, you can get the smooth hi refresh responsiveness that's on the latest iPads with ProMotion?

Subjectively I think the impact is greater on the iPad because you are touching the content directly rather than interacting by proxy.

With a mouse and keyboard, extremely nice for games, pretty nice for general desktop use.

 

[Robotronic]

I'm running an iHack with a 5500XT, Pro Display XDR, and Belkin VR cable. 6K works properly with DSC in Catalina, but is broken in Big Sur even with the just released 11.2 RC (20D53).

 

[turbineseaplane]

I'm running an iHack with a 5500XT, Pro Display XDR, and Belkin VR cable. 6K works properly with DSC in Catalina, but is broken in Big Sur even with the just released 11.2 RC (20D53).

Can you tell me more about this?

What is your output/connection situation on the Hack end of things?

Are you going from DisplayPort from your GPU and getting full 6k/60hz?

Or do you have a Hack with a thunderbolt add-in card (titan-ridge type of thing)?

 

[Robotronic]

Can you tell me more about this?

What is your output/connection situation on the Hack end of things?

Are you going from DisplayPort from your GPU and getting full 6k/60hz?

Or do you have a Hack with a thunderbolt add-in card (titan-ridge type of thing)?

Sapphire Pulse 5500 XT GPU
Belkin Charge and Sync cable
Pro Display XDR

The Belkin cable is the magic sauce here. It's apparently made for Huawei VR goggles, and is only sold in China. You can order online here: https://www.giztop.com/belkin-charge-and-sync-cable-for-huawei-vr-glass.html but it'll take a while as it ships direct from China. I ordered with express shipping and it took 10 days. That cable connects to the GPU DisplayPort port and two USB ports on the iHack, and connects to the XDR directly with a USB-C connector. I believe the extra USB connections provide power for the cable as well as a USB connection to the USB ports and controls in the XDR to provide True Tone and brightness control. I have the Logitech 4K camera made for the XDR, and it works with the Belkin cable. (This cable also works with the LG UltraFine 4K and 5K monitors, and provides access to brightness control as well as the built-in camera and speakers.) With this setup, yes, I get full 6K@60hz using DSC (but only in Catalina, as DSC appears to be broken in Big Sur, which is of course the topic of this thread).

I chose this GPU because it has three DP ports (and one HDMI), so I can connect the XDR with the Belkin cable, and I also have two LG UltraFine 5K displays connected via passthrough with a Titan Ridge card in the iHack. Only downside is that the 5K displays run scaled - 5120x2880 scaled output (UI is 2560x1440 HiDPI) but actual resolution of 4096x2304, which is coincidentally the native resolution of the LG 4K. The difference in clarity/sharpness is noticeable, but acceptable to me to achieve this much screen real estate. The True Tone feature applies to the LG 5K displays as well, and I hacked together some scripts to synchronize brightness control between all three displays, so I can adjust them all at once.

 

[turbineseaplane]

@Robotronic

Thank you for the very detailed reply

Shoot - I'm looking for a 5k solution (XDR is overkill for me on features, size, price - all of it)..

I really hope Apple has a 5k first party solution in the works -- and/or that the UF 5k gets updated to a more modern approach than the dual-DP tiled thing they have going on.

 

[Robotronic]

@Robotronic

Thank you for the very detailed reply

Shoot - I'm looking for a 5k solution (XDR is overkill for me on features, size, price - all of it)..

I really hope Apple has a 5k first party solution in the works -- and/or that the UF 5k gets updated to a more modern approach than the dual-DP tiled thing they have going on.

You can run a single LG 5K UltraFine at true 5K resolution by connecting two DP ports from the GPU passing through to the Titan Ridge card, and then only the one display connected to the Titan Ridge. The two DP signals are combined into one to get the 5K resolution, since the LG 5K UltraFine does not support DSC.

 

[turbineseaplane]

You can run a single LG 5K UltraFine at true 5K resolution by connecting two DP ports from the GPU passing through to the Titan Ridge card, and then only the one display connected to the Titan Ridge. The two DP signals are combined into one to get the 5K resolution, since the LG 5K UltraFine does not support DSC.

Yeah - problem for me is that my Hack is a mini-ITX build and I don't have space for a GPU + a TR card

I think I might try to find a UP2715k or z27q perhaps

 

[Robotronic]

Did some more testing with my setup on the latest 11.2 RC3 (20D64) and found that if I connect the Pro Display XDR using the included Apple TB3 cable via pass through with my Titan Ridge card I can get full 6K with DSC enabled, it's only the Belkin VR cable that no longer works.