Connecting Mac Pro with NVIDIA GeForce GTX 9XX to Apple Thunderbolt Display

I'm finding conflicting information about this topic on the web, so I thought I'd raise the question here.

I'm wanting to use an Apple Thunderbolt Display with an NVIDIA GeForce GTX9XX series card in a MacPro and/or eGPU box. I figure I could use this StartTech adapter to connect the Apple Thunderbolt Display to the Display Port of the card:

https://www.bhphotovideo.com/c/product/945120-REG/startech_dp2mdpmf6in_displayport_adapter_6.html

However, I've found many websites that claim this doesn't work, and one lone comment on the link above under Q/A that said it does.

To be clear, I understand that I wouldn’t be able to send a Thunderbolt signal to the Apple Thunderbolt Display using any of the outputs from the NVIDIA display adapter.

I figured I could simply adapt the larger format DisplayPort to the Mini-DisplayPort and get it to connect that way. That is assuming that the regular DisplayPort and Mini-DisplayPort are essentially the same connection/protocol with just a different interface size.

Is what I'm trying to do possible and if so, will this adapter work, or do I need to buy something different?

In short, you can't.

This is because the Thunderbolt Display is a bit of a misnomer. It's actually a Thunderbolt Dock with a display attached to it.

The requirements for the TB Display, per Apple are as follows:

If your Mac has Thunderbolt ports, you can use a Thunderbolt display in macOS or Boot Camp. System requirements to use your Thunderbolt display in macOS:

• A Thunderbolt-capable Mac
• The latest software and firmware updates for your Mac
• OS X v10.6.8 Snow Leopard or later

System requirements to use your Thunderbolt display in Boot Camp:

• A Thunderbolt-capable Mac
• The latest software and firmware updates for your Mac
• OS X Lion: Boot Camp 4.0 is included with Lion OS X v10.6.8
• Snow Leopard: Boot Camp that’s updated to version 3.3

(Emphasis mine)

If you look at the ports of the TB Display, you will notice there are no "display" type ports (DP, mDP, DVI, HDMI, etc). Just TB, USB, FireWire and Network. The Display adapter is actually "embedded" in the display itself.

This is one of the reasons why you cannot connect an Apple Thunderbolt Display to a PC

I figured I could simply adapt the larger format DisplayPort to the Mini-DisplayPort and get it to connect that way. That is assuming that the regular DisplayPort and Mini-DisplayPort are essentially the same connection/protocol with just a different interface size.

This is correct. However, what you are missing that that the Thunderbolt Display doesn't accept DisplayPort or mini DisplayPort signaling. Your source has to be Thunderbolt to begin with.