I have an B550 Aorus Pro AC motherboard with a Ryzen 5800X CPU. The first PCIE slot has my RTX 3080 GPU in it and both of the M.2 slots have drives in them. The second M.2 slot disables the second PCIE slot, it is either one or the other. That leaves the last PCIE slot, which according to the manual runs in x2 through the south bridge. I want to add another M.2 drive if I can, and my question is, if I get an adapter to put an M.2 drive in the last slot, will it work? I think not, since all the adapters I have seen say they need X4 at least, but I am not sure.
If you go this route get a good enclosure with an rtl9210b chipset.
I bought like 5 of these, they're the only adapter I've found that's cheap, good, all metal (so the controller doesn't overheat), and has firmware without issues with TRIM on Linux: https://a.aliexpress.com/_mM2U8U6
This one benefits from adding a dab of thermal putty (or a pad) under the chipset so it can use the case as a heatsink. Same deal with the drive, a blob of putty on top to connect the drive to the lid helps performance.
Thank you :)