- you might need to [cut the B-key from the socket to force it accepting the M-keyed SSD](’
https://www.reddit.com/r/thinkpad/comments/llsq0h/comment/hw1fviq/’
).
With that said, for T480, it would be better to replace the existing SATA HDD caddy with an official NVMe M.2 caddy (part number: 01AX994 or 02DL692) and the connector cable with a NVMe compatible one (part number: 00UR496), IMHO. Not only you can use regular 2280 SSDs in that way, but you can also avoid thermal as well as PCIe bandwidth throttling.