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Unable to disable discrete GPU and boot Big Sur

Joined
May 8, 2020
Messages
11
Motherboard
ASROCK Z390 Phantom Gaming-ITX/ac
CPU
i5-9600K
Graphics
PowerColor RX 5700
Mac
  1. iMac
Mobile Phone
  1. Android
I have a new Big Sur 11.1 Open Core build with everything working.

- ASROCK Z390 Phantom Gaming-ITX/ac (Bios is v4+)
- Big Sur 11.1
- i5-9600k
- RX 5700

Currently running the RX 5700 and looking to upgrade to (surprise) a 3080 for gaming in my dual boot. I know this isn't supported, but I'm trying to test out disabling discrete graphics and using Intel graphics before I shell out the cash.

I've tried -wegnoegpu and the "DeviceProperties" method. Both methods fail on boot with some funky screen. I can't see the verbose logging because the screen gets scrambled (is there a way to get the kernel panic logs otherwise?). My Bios is set so that integrated graphics is the primary output.

I can try the SSDT method, but I've also seen people mention that you might have to install Big Sur with the graphics card physically removed from the system. This sounds like quite a bit of work so wanted to check here on options first. Is it possible that since I installed Big Sur with the 5700 attached that my integrated graphics aren't properly configured?
 
Joined
May 8, 2020
Messages
11
Motherboard
ASROCK Z390 Phantom Gaming-ITX/ac
CPU
i5-9600K
Graphics
PowerColor RX 5700
Mac
  1. iMac
Mobile Phone
  1. Android
Adding config.plist
 

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  • config.plist
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Joined
May 8, 2020
Messages
11
Motherboard
ASROCK Z390 Phantom Gaming-ITX/ac
CPU
i5-9600K
Graphics
PowerColor RX 5700
Mac
  1. iMac
Mobile Phone
  1. Android
I did try this, and get a failed boot as well. At this point, I'm just looking for the right approach.

Should I go through framebuffer patching tutorials? Has anyone successfully got Big Sur to boot on iGPU while a dGPU is attached and enabled in BIOS?
 
Joined
Aug 3, 2012
Messages
20
Motherboard
Gigabyte Z77X-UP5 TH
CPU
Intel Core i7-3770K Ivy Bridge 3.5GHz
Graphics
Gigabyte GTX 980 G1 Gaming
Mac
  1. iMac
  2. MacBook Pro
  3. Mac Pro
Mobile Phone
  1. iOS
I'm in the same situation, but with two Nvidia GPUs: one supported and the other is not in Big Sur. Have you had any success?
 
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