System specs
15" MacBook Pro Retina (Mid2015):
Processor 2.8 GHz Quad-Core Intel Core i7 (I7-4980HQ)
Memory 16 GB 1600 MHz DDR3
iGPU: Intel Iris Pro 1536 MB
dGPU: AMD Radeon R9 M370X 2 GB
Win 10 Home: 1903 18362.295
eGPU hardware
Razer Core X + Nvidia GTX 1080 Ti
Thunderbolt 3 to Thunderbolt 2 Adapter
Thunderbolt 2 Cable (2m)
External Monitor: LG 34wn80c-b
Hardware pictures
Installation steps
Install Windows 10 - 1903 18362.295
Download latest DDU.
Reboot into safe mode.
Run DDU (remove GPU drivers for AMD). Then restart into normal Win10.
Install Nvidia drivers.
Create bootable apple_set_os.efi
Reboot with apple_set_os.efi, follow prompt and external monitor turned on.
Benchmarks
CSGO about 200fps
Valorant about 100fps
Comments
Unsure if it's important but I connected my thunderbolt cable closer to the charging port.
I originally tried to get my egpu running with an amd card (5700xt) but couldn't figure it out, constant errors such as error 12 and 43. Installed the nvidia card and it worked relatively easier comparatively. I was faced with error 31 but once I tried apple_set_os.efi it worked with no issues. Now I'm able to boot without apple_set_os.efi but still do so as user @macnexus suggests the laptop runs quieter and cooler when the dGPU is deactivated through apple_set_os.efi