hi Guys,

Today,
I tried to clean installation again on this MOBO. (BIOS 1.20, Using default settings)
The successful procedure is below.

1. Using "Media Creation Tool", prepare the latest USB installation media. (Version 1709)

2. Install the OS without connecting to the network.

3. Please still be offline after installation. Make sure that all of your GPUs are visible in Device Manager. (The NVIDIA driver has not been installed yet.)

4. Disable all HD audio devices. (Optionally, set HackFlags and reboot.)

5. Connect to the network. Install the driver automatically in device manager, or install Nvidia genuine. (Keep all HD audio devices disabled even after driver installation.)

6. If HackFlags does not set and Code12 still indicated, try HackFlags and reboot.

But I do not know if this is effective with AMD's GPU.
Can anyone verify it.

ty