2018 Mac Mini [8th,4C,B] + RX Vega 56 Nano @ 32Gbps-TB3 (Gigabyte Gaming Box) + macOS 11.0 & Win10 2004 [itsage]
I've been testing macOS 11 Big Sur Beta on a few Macs and noticed the firmware changes have made things more unpredictable booting into Windows with the eGPU connected (cold-plug). Unless you use Win10 1903 V1 (18362.30 - .295), hot-plugging an AMD eGPU would result in error 12. The modified apple_set_os.efi loader works in keeping the Intel iGPU activated but Windows would have issue with either detecting an active Thunderbolt device or throwing different errors (43 and 12). I tried timed hot-plug too but there's no real success. What finally worked for my 2018 Mac mini with macOS 11 firmware is a new error 12 workaround, HackFlags 0x600 registry edit.
Late 2018 Mac mini – i5-8500B/UHD Graphics 630 iGPU/32GB RAM/256GB SSD
I always use the 2018 Mac mini with this ASUS portable USB-C monitor. It provides boot screen directly off the Intel iGPU through a USB-C port. In macOS 10.15 Catalina eGPU overview, I mentioned Apple introduced eGPU boot screen support for the 2018 Mac mini. This feature was very buggy and short-lived (worked from macOS 10.15 Beta to 10.15.1). Unfortunately there's no fix in sight.
In macOS 11 Beta [20A5384c], this eGPU setup worked plug-and-play. Intel UHD Graphics 630 iGPU powers the ASUS USB-C display while RX Vega 56 Nano eGPU powers the Samsung 34" monitor through DisplayPort. The Samsung monitor has two Thunderbolt 3/USB-C monitor inputs (85W & 15W PD). I currently use one DisplayPort to USB-C connection for the R9 Nano in the TB3 test PC (Gigabyte X99 Designare motherboard).
In Windows 10, there are a couple of options to get a Radeon eGPU going. If you install Windows 10 1903 V1 ISO through Boot Camp Assistant then disable Windows Updates, you should be able to hot-plug the eGPU and install Radeon graphics drivers with little issues. Once this step is done, shut the system down and switch the monitor connection from the Mac mini to the eGPU. The iGPU gets deactivated during boot as soon as Windows recognizes the eGPU.
I wanted to test a newer version of Windows 10. At the moment my 2018 Mac mini is enrolled in Insider Preview Dev and it's running version 2004 (OS Build 20226.1000). These are the basic steps I took to get this setup going:
- Boot into Recovery mode to disable SIP through Terminal. Open Startup Security Utility to set Secure Boot to No Security and External Boot to Allow booting from external media [in Recovery]
- Download and install Windows 10 ISO through Bootcamp Assistant [in macOS]
- Run DDU with Admin privileges to disable Windows auto-installation of drivers [in Windows]
- Hot-plug eGPU to Thunderbolt 3 port #1 closest to the Ethernet port [in Windows]
- Confirm a new Microsoft Basic Display Adapter in Device Manager then install Radeon drivers [in Windows]
- Download and run HackFlags 0x600 .REG file [in Windows]
I installed the latest WHQL Adrenalin Software and drivers, version 20.9.1. The eGPU performance with these newer Radeon drivers is inconsistent. Take a look at Unigine benchmark numbers comparing 20.9.1 to 20.4.2. Superposition is especially strange when it seems the FPS was capped at 40.
|20.4.2 Drivers||20.9.1 Drivers|
Using an AMD Radeon eGPU in Boot Camp is a constant battle but it's somewhat rewarding when you get it working. If you're in a similar situation (error 12 with macOS 11 firmware), give Hackflags 0x600 a try and let us know whether this solution works for your Mac.
Thank you for sharing your findings.
I am using Big Sur 11.0 Beta 20A5384c and Bootcamp Windows 2004 19041.546 with my Mac Mini 2018 and the PowerColor Mini Pro 240 FU since several days very succesfully - I am absolutely satiesfied. No error codes, no black start up screen loading Windows (cold plug), no update challenges with both operating systems at all.
Although it seems, that the AMD Vega 56 Nano is not easy to get in Germany, I am planning to replace the built-in RX 570 with it. However, if I read your experiences I am not sure if it is worth a try. May be I should not change a running system for a limited enhancement of power.
What do you think?
@hans-st, Glad to hear it's working well for you. Radeon ITX cards are not widely available unfortunately. If you were to replace the RX 570, I'd recommend RX 5600 XT rather than the Vega 56. I bought one for the VisionTek mini eGFX which is the same as PowerColor Mini Pro. It works very well with my work laptop, 2019 13-in MacBook Pro [build link].