Apple Thunderbolt Display goes black on Windows 10 login screen

I have ASRock X570 Phantom Gaming ITX motherboard with Thunderbolt 3. I want to use Apple Thunderbolt Display with Windows 10. After installing the drivers it started working however it does not work on Windows login screen, it goes dark and there's no way to login.

Right now it goes like this:

  1. Turn on PC
  2. See ASRock logo on Apple Display, monitor is working before OS started booting. Windows 10 starts booting.
  3. Login screen is supposed to show up, but display goes black (gets turned off). Tried entering PIN blindly to log in, but didn't help.

Things I've tried:

  1. Disabled login screen so that Windows 10 goes to desktop on boot. Still same result, screen goes dark and never turns on.
  2. Booting with HDMI and Thunderbolt monitors. It works, login screen shows on HDMI, Thunderbolt goes dark. After login both monitors start working.
  3. Booting with Thunderbolt cable disconnected then connecting it after boot. Monitor turns on, but starts to flicker every ~10 seconds. It seems hot plugging is not possible.

Current workaround: I disconnect Display Port cable going from GPU to motherboard. Motherboard thunderbolt cable to Apple monitor is still connected. Windows 10 is configured to skip login and go straight to desktop. I turn on my PC, wait 30 secs to make sure it boots up then connect DP cable. Everything works fine.

Problem

How to fix / debug Apple Thunderbolt Display going dark during Windows 10 login screen?


Solution 1:

I was able to solve this. ASRock Phantom Gaming ITX/TB3 motherboard has a Thunderbolt chipset called "Titan Ridge" (newer). Apple Thunderbolt Display has a version called "Alpine Ridge" (older). This difference was the cause of the flicker.

The solution is to have an intermediate Thunderbolt dock that has "Alpine Ridge" chipset. For example:

PC Motherboard TB3 -> Apple TB3 to TB2 converter -> TB2 dock with Alpine Ridge -> 
Apple Thunderbolt display

I'm using ATEN US7220 dock which is also a KVM switch. The end solution is really neat: On my desk I now only have a monitor, a mouse and a keyboard. My Mac and PC and Dock are hidden in the shelf. With single button press on the dock I can instantly switch between computers.

No multiple mouses and keyboards. No multiple monitors. No tinkering with the wires. Just click and you have a different computer! Magic.