I wanted to post my experiences with putting the Micron 9300 Pro drives in a Mac Pro 5,1 since it looks like this discussion is only about 7,1.
Using both the Startech card and the Sonnet dual card, the 7.68TB model works fine, and gives around 1500MB/s read and write (AJA and Blackmagic). Except, oddly, if I put it in the x16 slot using the Startech card, I only get half speed. Just that slot. And the Sonnet in that slot is fine. Seems like it’s running PCIe 1 speeds. No trouble; use another slot.
Then the weird(er) thing. I decided to get the 15.36TB model. Installed, turned the Mac on, and... nothing. No chime, no screen. Doesn’t matter which adapter card, doesn’t matter which slot, doesn’t matter which 5,1 (I have two). Put the smaller SSD in and it chimes and boots. So I gave up and am going to use the drives in a Sonnet PCIe Thunderbolt chassis hooked to an M1 Mini. That works fine. I did not test on a Mac Pro 7,1.
Long story short: Micron 9300 Pro 15.36TB prevents Mac Pro 5,1 from booting.