I finally was able to do this project - RTX in a Bootcamp. I found out that the information for this topic is somewhat spread all over internet and decided to post here my way of how to do it so that it may come in handy for others who may face some problems during this process.
To have a RTX card working in Bootcamp on a cMP you have to have the following:
- It is essential to upgrade boot ROM version to 144.0.0.0.0
- To do this you have to have boot ROM version MP51.089.B00, “metal” supported card and upgrade your firmware via Mojave Installation (you don't nned to actually install Mojave)
- List of metal supported cards can be found all over internet. AMD’s RX 500 series are supported, as well as nVidia cards of 600, 700, 900 series are metal supported. I bought ZOTAC 710 GT for just 30 USD and upgraded the firmware. This card does not require additional power, it is one slotted and works perfectly in High Sierra (or even lower macOS, did not check that)
- I had a problem with firmware upgrade, when I clicked "Shut Down" button for the firmware to be installed and my cMP to be shut off - nothing happened. The problem is that my drive was not partitioned in APFS. I just clean installed High Sierra onto APFS partition drive, downloaded Mojave Installation from App Store and was only then able to upgrade firmware. Otherwise the firmware would not upgrade.
- After you upgrade your firmware, you can proceed with Windows 10 installation in UEFI mode. You don’t need to do the Legacy mode, only UEFI via USB installation, otherwise RTX would not work.
- After you install Windows 10, install Bootcamp drivers.
- After Bootcamp drivers installation is finished, you may encounter a problem of freezes at the Windows 10 login. It happens because of the "MacHALDriver.sys" that had to be renamed or deleted for the freezes to go away. The path to the folder would be in windows/system32/drivers.
- Plug in your RTX and install the drivers.
- I found a workaround when the display is blank but the system is running. i installed Teamviewer prior to this and was able to login into Windows even with the screen being blank.
- RTX card supports boot screen, therefore there should be no problem switching the OS with alt key. Or, the other scheme should be choosing the macOS from within the Bootcamp control panel and switching the cable to nVidia 710 and booting to Bootcamp via RTX from bootscreen and alt key.
This way we have a working RTX card in Bootcamp. I am hoping that someday the drivers for RTX would be released for the macOS so that we will have a great card with boot screen working perfectly in Bootcamp and macOS. Let's just hope for it.