How to Install Bootcamp on Mac Mini 2018 with eGPU

I made attempts to install Bootcamp on Mac mini. However, the entire process sucks. Discussion on the net is inconsistent with new version of macOS and Windows 10, making it more difficult to debug. I wrote down the steps to install Bootcamp successfully. Hope it helps.

Preface

Though almost everything can be done on macOS, I still want to play games on Steams. Especially The Witcher 3. Buying another PC set is not a good deal for me. Then I made attempts to install Bootcamp on Mac mini. However, the entire process sucks. Discussion on the net is inconsistent with new version of macOS and Windows 10, making it more difficult to debug. I wrote down the steps to install Bootcamp successfully. Hope it helps.

Problems List

  1. Bootcamp Assistant always reports error while copying the install files
  2. Unable to display through eGPU
  3. Unable to complete the Bootcamp Driver installation after entering the Windows 10

As long as the problems listed above are solved, the experience to play game on Bootcamp is not bad. I could play The Witcher 3 smoothly with eGPU.

Hardware

  • Machine: Mac mini 2018, with 16GB memory, 256GB SSD
  • eGPU: AKITIO Node + AMD RX 570 8G
  • macOS version: Catalina 10.15.4 or newer
  • Direct link to screen through eGPU with DisplayPort

All set above work well in macOS, but with some restriction:

  1. FileVault must be disabled, or you could only see login screen with built-in HDMI output due to T2 security chip.
  2. eGPU must not be detected while booting or macOS will go black and freeze. If met, the only way to solve it is to force restart. I suggested with eGPU connected, wait for at least 5-6 seconds after booting then turn on the eGPU.

With these steps, login screen now can be displayed in my daily life. Also under macOS Catalina 10.15.4, AMD RX570 can output HDR signal.

Please connect the Thunderbolt cable to the two ports which are most closest to ethernet port. It was said that bandwidth differs but no reliable information sources.

Windows Installation Location: Internal vs External disk?

Initially, I prefer to install Windows on external disk with these concerns:

  1. APFS filesystem structure is complex. I was afraid to break its integrity and stability after cutting another Bootcamp NTFS partition.
  2. I have seen many unlucky cases that Bootcamp partition was broken after macOS upgraded, or Windows upgrade broke the macOS boot.
  3. Limited disk space.

There are many blog articles writing about how to install Windows 10 on external disk, which mainly depends on Windows To Go. To boot into Windows 10, hold down the Option key while booting and select the external disk. The product GameToGo is similar way with all needed files packed. However, I found some flaws in the Windows To Go installation method:

  1. Startup Disk Preference in macOS is unable to detect Windows 10 on external disk. Hence it’s impossible to reboot into Windows 10 under macOS.
  2. Vice versa, Bootcamp control panel under Windows 10 is unable to detect macOS either.
  3. I use wireless mouse and keyboard. But it’s necessary to use wired keyboard to hold down Option key. It is stupid to reconnect the wired keyboard during every OS switch. There is no such problem on MacBook.
  4. The time to hold down Option Key is a little hard to catch. Sometimes When I acted too slowly, I had to restart the Mac mini after entering into macOS. It wasted much time especially when I tried and error during installing Windows and eGPU.

Afterwards, I adopted the Bootcamp Assistant in macOS to cut partition for Windows Bootcamp. There are some benefits:

  1. I can select to switch to Windows in Startup Disk Preference under macOS. Also if Bootcamp support software is installed correctly in Windows, It is able to reboot back to macOS under Windows.
  2. Official Apple Magic Keyboard, Trackpad, or Magic Mouse can be shared directly between two OS without re-configuration if Bootcamp driver is installed correctly. It’s coooooool !!!

With limited disk space, I set my steam game library on external SSD, and formatted it into exFAT to ensure the accessibility between macOS and Windows.

Preparation

  1. Please update the macOS to newest
  2. Windows 10 install ISO, at least version 1903
  3. Leave enough free disk space or Bootcamp Assistant will unable to partition
  4. Wired USB mouse and keyboard, you can connect the Magic Keyboard and Mouse with Lightening cable.
  5. Please output display through Mac mini built-in HDMI. We configure the eGPU at final stage.
About optimal Windows 10 version, opinions on the Net are divergent. There are two crucial factors:
1. Old version macOS Bootcamp Assistant adopted FAT32 to cut Windows install partition. FAT32 had maximum file size restriction 4GB. Windows 10 ISO install file size exceeds this restriction after version 1803. Hence Bootcamp Assistant will fail while copying install files on FAT32 partition. However, the Bootcamp Assistant under newer macOS already solved it by using exFAT.
2. Old version Windows 10 had poor support on eGPU. It was prone to error 12 or error 15. In theory support on eGPU is enhanced on newer Windows 10.

Steps by steps

1. Turn off the T2 security

Please follow this official documentation to turn the “Secure Boot” to No security (I did not try Medium Security). If Windows is not installed on external disk, no need to adjust the “External boot” configuration.

2. Execute the Bootcamp Assistant

Search the “Bootcamp Assistant” in Spotlight, run it. Do not continue at first. Download the Windows Support software to external disk or anywhere which Windows can read.

Experienced users then would click on “Next Step” and “Next Step”. In theory, Bootcamp Assistant would complete everything.

But I never enter the last step. Fxxk.

Each time when I ran into the last step that Bootcamp Assistant prepared to copy the support software, it always reported error, then started to reverted back including erasing out Bootcamp partition. At first I thought it was due to the limitation of FAT32 maximum file size. However, exFAT partition formatting could be observed through “Disk Utility” during the installation process. Newer macOS version already solved this issue. So, what on earth happened?

The steps in detail Bootcamp Assistant does:

  1. Format two additional partition outside of system partition, one is “Bootcamp”, another is “OSXRESERVED” which Windows 10 install file is copied temporarily.
  2. Copy the Windows Support Software
  3. If all copied, reboot from “OSXRESERVED” to enter Windows 10 installation and use “Bootcamp” as the Windows 10 install target partition.

I guess that something went wrong while copying the Windows support software. Copying from install ISO fo “OSXRESERVED” seemed to run smoothly without problems.

Hence, what I did to solve this issue is Force quit the Bootcamp Assistant!!!. The time to force quit is just after Windows 10 iso files was copied completely.

We then can boot into “OSXRESERVED” manually and install pre-downloaded Bootcamp Driver.

3. Reboot to Windows 10 installation

After rebooting, please hold down Option Key until boot menu pops up. In previous steps are done correctly, there will be new item named “Win10”. Enter it.

1. Please use wired mouse and keyboard
2. Must enter in boot menu at first time after rebooting!!! If you miss it and still boot into macOS, the just partitioned “OSXRESERVED” will be erased. Then only a blank “Bootcamp” partition is left. The whole preparation need to be executed again.
3. Please use the Mac mini built-in HDMI before entering Windows 10 installation

At the beginning of Windows 10 installation, the program is unable to read Apple built-in SSD. You need to search for SSD driver in pre-downloaded Windows support software folder. Load it then internal disk can be read.

Select the pre-allocated “Bootcamp” partition and re-format it into NTFS. Till here, Windows 10 installation should run smoothly without problem. Here we go!

4. Reboot into Bootcamp, Install Bootcamp Driver

After rebooting, Option key still need to be hold down to select Bootcamp to boot. After Windows 10 installation is completed, open the folder of pre-downloaded Bootcamp Driver.

Do not click on Setup.exe!!!

Please cut the folder “drivers/Apple/AppleUSBVHCI” to the Desktop before clicking on the Setup.exe or it will hang during installation. After Bootcamp Driver is installed, reboot to Windows and install the AppleUSBVHCI driver. In the folder only one of three file can be installed through right click context menu.

If all is set correctly, there will be Bootcamp Control Panel in system tray. “Reboot into macOS” option is included there. There might be update on Bootcamp control panel. You should install it.

Till now, you can find the Magic Keyboard, Trackpad, or Magic Mouse already are listed out in Bluetooth under Windows.

5. Install eGPU with AMD RX 570

Please download the newest Adrenalin driver from AMD official site. Do not insert the eGPU directly and wait for the Windows Update to install driver.

Insert the eGPU and execute the install program just downloaded. If eGPU is successfully detected then the installation process should run smoothly. There may be error reported after the installation is done. Don’t worry, turn off the Mac mini and remove the HDMI cable. Leave the eGPU connected. Then turn on the Mac mini. In theory Windows 10 will detect eGPU and load AMD driver automatically. (There will be black screen for a while without Windows logo, be patient. )

Why suggest newer version of Windows 10? It was said that error 12 or error 15 often emerged on previous version Windows 10. Possible cause is insufficient I/O resource. If met, leave the Mac mini with the less peripheral devices connected the better. Newer Windows 10 version seemed improved on these conditions.

Epilogue

It’s quite tortuous to try Bootcamp installation on my Mac mini 2018. Actually, with my heavy work load, from start to success cost me about one year. I even already bought another display. With successful Bootcamp configuration, I can now suppress my impulse to buy another Intel NUC to play PC games. However, I sadly (or pleasantly?) found that another stage of my job (senior resident doctor of radiotherapy) will come. There is no much time left for me to play game.

Hope this article helps.