2013 Mac Pro (FP D500 x2) [3rd,6C,E] + RX Vega 56 @ 16Gbps-TB2>TB3 (Razer Core X) + macOS 10.15 & Win10 1809 [jcp-123]  

1. System specs

• Mac Pro 2013 / Intel 6-core Xeon E5-1650 @ 3.50Ghz / Dual AMD FirePro D500
• 1TB SSD (Sabrent PCIe M.2 upgrade)
• 16GB DDR3 RAM
• macOS Catalina (10.15)
• Boot ROM 133.0.0.0.0
• Bootcamp partition with Windows 10 Home version 1809 OS build 17763.1039
• HP2210i (1080p) monitor on TB2 port 1

 2. eGPU hardware

• Razer Core X
• Sapphire Vega 56 8GB
• Apple Thunderbolt 3 to Thunderbolt 2 adapter
• Cable Matters TB2 to TB2 cable, 1m
• TB2 to eGPU on TB2 port 5
• Iiyama PL2792Q (1440p) monitor

3. Installation steps

3.a macOS eGPU setup

csrutil disable (or if required: csrutil enable)

Install and run Purge-wrangler - easy and works a dream

3.b Windows 10 eGPU setup

Step 0. Install Windows version 1809

Version 1903 cripples eGPU is some way. Therefore you will need to install or rollback to 1809

Download the 1809 ISO image from Microsoft download site (or wherever)

Step 1. Create a dsdt-modified.aml DSDT file with a 36-bit root bridge

#step1

Steps i, ii, iii then

Option 1: Intel Method i, ii, iii, iv

Note my own DSDT-modified.dsl compiled without error after one minor change so I did not need to use the pre-compiled one.

Step 2.  Load your dsdt-modified.aml as registry override or in-memory substitution

#step2

Option 1, steps: i, ii, iii

Step 3. Confirm success with a ‘Large Memory’ area in Device Manager

#step3

Success!

Note that the desktop now shows the following in the bottom right-hand corner:

Test Mode

Windows 10 Home

Build 17763.rs5_release.180914-1434

Step 4. Disable PCI Resources

I then had many hours of Error code 12 or Error code 43 issues. Progressively disable/enable PCI-to-PCI Bridges. Finally achieved success with four disabled:

1. PCI slot 4 (PCI bus 21, device 5, function 0)

2. PCI bus 17, device 10, function 0 

3. PCI bus 21, device 0, function 0

4. PCI bus 0, device 30, function 0

Step 5. Bootcampdrivers

Head over to bootcampdrivers.com and download and install the latest AMD driver.

It is only after these drivers have been applied will the eGPU and second monitor work.

4. Performance

Luxmark / macOS

2xD500 = 16,743

2xD500 + Vega 56 = 43,026

Luxmark / Win10

2xD500 = 17,983

2xD500 + Vega 56 = 46,620

5. Side Effects

Windows machine will not mount external hard drives

6. Comments

I play World of Tanks on this rig and am able to load the full HD version of the game. All settings are at 'Ultra' and I get >80 fps in most scenes.