There are community threads with details — there are more things to worry about than just the power supply, but it's the biggest and weirdest one. The AMD boards also don't ship with a RTC battery for regulatory reasons, and they use a two-pin connector instead of a bare coin cell. There are further port limitations for connecting a display when no OS is installed or the mainboard wasn't initialized in the laptop case.

https://community.frame.work/t/recommended-watts-for-amd-coo...

https://community.frame.work/t/resolved-mainboard-standalone...

https://community.frame.work/t/amd-board-solely-in-the-coole...

The Intel boards also recommended 100W if there's no battery; the AMD issue is that _even with_ a 100W supply, performance is capped, and with a smaller power supply you might not be able to boot at all.