2019 SOLUTION: Apple Cinema Display (A1316) Mini DisplayPort Adapter

In case anyone was looking for on how to connect their Mac Pro with an upgraded graphics cards, look no further for I've done all of the work for you!

If you're looking into using with a newer MacBook with USB-C, https://www.youtube.com/watch?v=2n8R-PX5sGw&t=85s

COMPUTER

Mac Pro (Early 2009)

2 x 3.33 GHz 6-Core Intel Xeon

64 GB 1333 MHz DDR3

Jason's M.2 512GB (PCI Adapter)

Radeon Vega Frontier Edition 16 GB (running macOS Mojave 10.14.4 natively with boot screen)

16TB RAID 0 Storage

3TB Archive

1TB Samsung SSD T5 Scratch Disk via USB-C (PCI Adapter)

DISPLAY

Apple Cinema Display (A1316)

27-inch (2560 x 1440)

I used this adapter and extension cable to get it working!

https://www.amazon.com/gp/product/B003N3DTKY/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B01KRLQG2M/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

As far as the Apple Thunderbolt Display, I don’t own one to test. As far as the reading I’ve done, it won’t work because its Thunderbolt, as opposed to on the Cinema Display, Mini DisplayPort. It’s worth trying when the adapter is that cheap!