I have now installed a new AMD RX5700XT Anniversary Edition on my Mac Pro 5.1 (W3690, 24GB RAM). In the past i had a Vega 56, 980Ti and RX 580/590 but now the Windows 10 performance is incredible and nearly the same like my Gaming AMD PC from 2020!
I installed the EVGA PowerLink and from board two mini 6pin->8pin power cables and run some benchmarks without any problems. My old Vega56 need addional SATA power to run without crashes also the RX590 but the RX5700XT is not so power hunry.
The RX5700XT in reference design is in my opinion a very good upgrade for the Mac Pro 5.1, but you need Catalina!
I installed the EVGA PowerLink and from board two mini 6pin->8pin power cables and run some benchmarks without any problems. My old Vega56 need addional SATA power to run without crashes also the RX590 but the RX5700XT is not so power hunry.
The RX5700XT in reference design is in my opinion a very good upgrade for the Mac Pro 5.1, but you need Catalina!