Big Sur 11.1 update rendering 4k screen to only 720p

Question

Big Sur 11.1 update rendering 4k screen to only 720p

Hi,

I have a Mac Pro 16 inch. Here are the specs:

Hardware Overview:

  Model Name:	MacBook Pro
  Model Identifier:	MacBookPro16,1
  Processor Name:	6-Core Intel Core i7
  Processor Speed:	2.6 GHz
  Number of Processors:	1
  Total Number of Cores:	6
  L2 Cache (per Core):	256 KB
  L3 Cache:	12 MB
  Hyper-Threading Technology:	Enabled
  Memory:	32 GB
  System Firmware Version:	1554.60.15.0.0 (iBridge: 18.16.13030.0.0,0)
  Serial Number (system):	C0***D6R
  Hardware UUID:	0C7E0B78-F1ED-5E4C-9314-407FCEDDBFDE
  Provisioning UDID:	0C7E0B78-F1ED-5E4C-9314-407FCEDDBFDE
  Activation Lock Status:	Disabled

When I updated Big Sur to 11.1 my 4k screen by LG could not render more than 720 from usb-c LG provided cable. I had to switch to HDMI for it. I have 2 screens. Here are the specs:

AMD Radeon Pro 5300M:

  Chipset Model:	AMD Radeon Pro 5300M
  Type:	GPU
  Bus:	PCIe
  PCIe Lane Width:	x8
  VRAM (Total):	4 GB
  Vendor:	AMD (0x1002)
  Device ID:	0x7340
  Revision ID:	0x0043
  ROM Revision:	113-D3220E-190
  VBIOS Version:	113-D32207P1-019
  Option ROM Version:	113-D32207P1-019
  EFI Driver Version:	01.A1.190
  Automatic Graphics Switching:	Supported
  gMux Version:	5.0.0
  Metal Family:	Supported, Metal GPUFamily macOS 2
  Displays:
Color LCD:
  Display Type:	Built-In Retina LCD
  Resolution:	3072 x 1920 Retina
  Framebuffer Depth:	24-Bit Color (ARGB8888)
  Mirror:	Off
  Online:	Yes
  Automatically Adjust Brightness:	Yes
  Connection Type:	Internal
LG HDR 4K:
  Resolution:	5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)
  UI Looks like:	2560 x 1440 @ 30.00Hz
  Framebuffer Depth:	30-Bit Color (ARGB2101010)
  Main Display:	Yes
  Mirror:	Off
  Online:	Yes
  Rotation:	Supported
  Automatically Adjust Brightness:	Yes
  Connection Type:	Thunderbolt/DisplayPort
U2790B:
  Resolution:	2880 x 5120
  UI Looks like:	1440 x 2560 @ 60.00Hz
  Framebuffer Depth:	30-Bit Color (ARGB2101010)
  Mirror:	Off
  Online:	Yes
  Rotation:	90
  Adapter Type:	DVI or HDMI
  Automatically Adjust Brightness:	Yes
  Adapter Firmware Version:	ff.c1

How can I make it work with my USC-C with 60hz refresh rate.

[Personal Information Edited by Moderator]

Posted on Dec 15, 2020 11:45 AM

Reply

Answer 1

KMB_12

Community Specialist

Dec 18, 2020 7:45 PM in response to darthsidious1

Hi darthsidious1,

It sounds like you're having trouble with a connected display. If we have that correct, check out the following resource.

Get help with video issues on external displays connected to your Mac

Let us know if that helps.

Cheers.

Reply

Answer 2

burkard1

Level 1

4 points

Dec 23, 2020 9:07 PM in response to KMB_12

Hi @kareng12,

That's a general help article. This is a very specific issue caused by updating Big Sur to 11.1. You can find another issue report here: https://discussions.apple.com/thread/252174979

I'm experiencing the exact same issue. This is a critical problem.

Can you please tell me how to downgrade Big Sur back to 11.0? I was having no display issues then. Now, everything feels terrible as I'm capped at a 30Hz refresh rate. The setting is disabled (yes, I can see the setting by holding option and clicking scaled - but the dropdown to change refresh rate is disabled).

Reply

Answer 3

burkard1

Level 1

4 points

Dec 23, 2020 9:08 PM in response to KMB_12

This has rendered my near $1000 monitor unusable.

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Big Sur 11.1 update rendering 4k screen to only 720p

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