x870e motherboard ASUS ProArt X870E-CREATOR WIFI - Ryzen 9950x

[fabiosun]

Do you mean also no video input of your bios scanning?

or do you see opencore bootloader?

you must start from your USB pen or disk and you have to format it in a proper way for EFI

[khile]

1 hour ago, fabiosun said:

Do you mean also no video input of your bios scanning?

or do you see opencore bootloader?

you must start from your USB pen or disk and you have to format it in a proper way for EFI

 

So on the 4090 i see the bios and press F4 to boot from UEFI USB, and i see the bootloader showing Mac (usb drive) and my Windows installation. I then select Mac and both monitors go black i have left it for an hour while i did a few errands, and when I came back still the same black screens 

I formatted the USB as FAT32 and GPT using Rufus, like the below screenshot

 

see below video

 both gpu plugged into tv as other monitor was borrowed and needed to be returned (4090 on HDMI 4) (6600 on HDMI1)

Edited 5 minutes ago by khile

[fabiosun]

6 minutes ago, khile said:

So on the 4090 i see the bios and press F4 to boot from UEFI USB, and i see the bootloader showing Mac (usb drive) and my Windows installation. I then select Mac and both monitors go black i have left it for an hour while i did a few errands, and when I came back still the same black screens 

it could be normal if you use 4090

try to connect your monitor(s) to rx6600

you should also prvide a full installer and not a recovery installer because in tahoe your ethernet card could not work and a recovery installers needs a working one ethernet

[fabiosun]

then with my efi you should see a "dos" verbose scrolling lines

Boot menu i see there is from gtx 4090?

We should see it on RX 6600

usb pen seems to be formatted well