How to install macOS Big Sur with 2 Seperate SSD's?

[Sky.P]

Hey, since I have a new NVMe M.2 SSD for Windows, I wanted to use my old SATA SSD for macOS Big Sur. Unfortunately I don't have a plan how to do this. But I have a suitable EFI folder that is compatible with my PC. Should I reinstall Windows when I install macOS? I also don't know how to create a bootable USB stick for macOS Big Sur. Is there even a DMG file for it, or do I just have to update it via Catalina?

Sorry for my bad english

Translated with www.DeepL.com/Translator (free version)

 

[Shaneee]

Do you already have Catalina setup on the Sata SSD? If so then it's as simple as making sure you've got the latest patches, update OC/Kexts and run the update. If not then follow the Dortania guide which I'll link below, and install onto the Sata SSD. Unless you format the wrong drive during the setup there's nothing to worry about. I've installed Windows, Linux and macOS on different drives while the others are still connected without issues.

Making the installer in Windows | OpenCore Install Guide

 

[Sky.P]

No I don't have Catalina on my SSD there is no OS installed, I just need the USB stick to install it. will it destroy my EFI folder in any way?

 

[Shaneee]

No I don't have Catalina on my SSD there is no OS installed, I just need the USB stick to install it. will it destroy my EFI folder in any way?

The Windows EFI? No. If you mean an OpenCore EFI, Unless you've made it your self in preperation for installing macOS I suggest you follow the tutorial step by step and make your own.

 

[Sky.P]

So, i got it. macOS runs. But idk how to update to Big Sur. In the installer of big sur im getting only a black screen, no apple logo or other things

 

[Shaneee]

What GPU do you have?

 

[Sky.P]

I have the RX 5700 XT with display port connected monitor and HDMI monitor

 

[Shaneee]

Do you have the agdpmod boot arg at all?

 

[Sky.P]

To be honest I do not know, where do I set this and where do I see this

 

[Sky.P]

Well, i found it in the config.plist its on "agdpmod=pikera" is it right?

 

[Shaneee]

Yes that's correct. To make sure it doesn't break Catalina booting. Use a USB drive with a copy of the EFI on it and remove that boot arg to test.

 

[Sky.P]

Do I have to restart the update via Catalina first and then restart or just boot directly in this macOS installer

 

[Shaneee]

If you've still got the option in the boot picker for the update you can use that.

 

[Sky.P]

@Shaneee so i got Big Sur installed, but only one of my two monitors are working, do i have to look after the graphics card kext?

 

[Shaneee]

If you’ve still got that boot arg removed try adding it back in. Sometimes it doesn’t play well for the installer.

 

[Sky.P]

i think its added back in, but still only one monitor