RTX 3080 TI Windows Bootcamp 2020 iMac 27" 5K i9 10 core 5700 XT 16 GB eGpu Razer Core X Error 12 !!!  

@palbar12, Have you tried DDU to remove graphics drivers? I'd recommend disabling Windows auto detect and driver installation of new devices. 

@itsage, Hi , yes of curse !

I tried all guide and post in this forum.

I think I need a custom apple_set_os.efi  to disable AMD GPU and Intel 630 UHD and prefer RTX.

But I need some help !!!

Thickens very much !!!

sorry this https://egpu.io/forums/bootcamp/macbook-pro-16-windows-egpu-error-12-fix/

Well, i have the aorus gaming box 3080 ti, MBP 16 inch 2019 model, i9, and i’m stuck in error code 12.

reached for Apple, Nvidia and Microsoft supports, and the are all useless.

I don’t wanna take high risk that may cause to brake my MBP so i’ll wait hopefully someone get to a good solution to try it. 

So... the same issue with my MBP 13" 2020 (i7/32) + Razer Core X Chroma:

- I had 3080 and I didn't have any problems with it. 

- now after replacing the 3080 with the 3080ti I got error code 12

please somebody help us )))

UPDATE:

The problem with error code 12 was solved by installing Win 10 Pro 1903 V1 build from https://tb.rg-adguard.net/public.php

Everything started to work automatically without any issues

UPDATE 2:

I switched off auto updates on the 1903 V1, but then decided to try updating the system. And after installing 20H2 through win auto updates I got error code 12 again )))

@palbar12, I'm in the same boat, 2020 iMac with i5 3.3 and AMD Radeon Pro 5300 and I probably spent upwards of 10 hours trying to get a 3060 ti in a Razer Core X to work in Windows 10 via boot camp. I tried one guide after another and it was just one disappointment after another. Nothing but error code 12 over and over and over and over...

Some things I tried:

Plugging in after holding option and getting the boot selection (resulted in black screen and no OS loading)

Plugging in after the spinning circles thing and Windows logo showed up (error 12)

Plugging in after Windows loads (error 12) and trying to disable and enable literally every combination of devices in device manager (error 12)

Automate eGPU with cold plug (black screen) or hot plug (error 12)

DSDT (only to find it wasn't necessary because my Mac already has large memory allocation)

Registry HackFlacks (error 12)

Clean sheet reinstalls (error 12 all day) and avoiding boot camp drivers installing (still error 12)

Banging my head against a wall for several minutes (surprisingly, still error 12) 

@rolandoblomblando, Start with a good version of Windows which is Win10 1903 V1.

@itsage, @pkf , 

which of it ?

I tried both but still error 12 ...

help .. I also tested a 3080 FE but nothing.

Now I've got a 3080 ti ultra.

@palbar12, 18362.30 is the V1 version of Windows 1903. 

@itsage, I'm going to bite the bullet and try to do a clean reinstall with 1903 v1 as I feel like it's pretty much the only thing I haven't tried. I will let you know if it works.