The Mac Pro (2019) has a non-standard connector for on-board SATA power. These cables allow you to use it.
The 12” variety is intended for use with internal SATA-powered peripherals such as USB expansion cards, or anything else that’s mac-compatible but requires SATA power.
I can also do custom cables if, say, you want two drives and three cards. This might stress your motherboard, but it would also be very cool while it was doing it. (Sparks = very cool.)
Note that I have not tested any cards for Mac compatabilty and have no idea which ones work and which ones don’t. If you find one that does work (or doesn’t??) drop me a line and we’ll add them to a list or something. That’d be cool.
These cables are hand-made to order. Delivery can take a couple of weeks because of the sad reality of shipping during a global pandemic 🤷🏼♂️.