UPDATE: These are now for sale!

The 2019 Mac Pro features power connectors for both PCIe and SATA internal devices, but they are not standard connectors.

The PCIe connectors provide 12v and ground, and the SATA connectors provide 5v, 12v and ground (but curiously do not provide 3.3v, which is specified in the… specification… but which apparently most modern drives do not require).

Pinouts

Note that the front fans do not require a dust filter and dust will not accumulate. Ahem.

Connectors

I found the appropriate plugs for the SATA power connectors and the 8-pin PCIe connectors (I didn’t get any 6-pin connectors).

But hang on what about storage

Well, you could buy that stupid 8TB drive and cage for ridiculous money, or you could do what I did and make some cables and a bracket to hold two SSDs.

I want to find some shorter SATA cables, but overall I’m pretty happy with this. The printed prototype works really well (at least for solid-state drives), but does tend to warp over time with the heat and uneven load.

These are now for sale!