I have been using an old PC as NAS and running docker containers (Immich, Nextcloud, paperless-ngx etc.). I got 5 3.5" HDD disks and a Nvme. Even on idle, I am consuming 50-60w. A friend of mine is selling a Qnap NAS which is a dedicated machine and probably consumes less power, although I don’t know if it’s worth it.
It’s 6th gen i5 processor with gigabyte motherboard. And Qnap is ts-531x.
I switched from an I3-530, nominal TDP 73W, to an N-100, nominal TDP 7W, and power from the wall didn’t change at all. Even the i3 ran around 0.1 CPU load, except when transcoding, and I’m left with the impression that most of the power goes into HDDs, RAM, maybe fans, and PS losses. My sense is that the best way to decrease homelab power use is to minimize the number of devices. Start with your seyrver at 60W, add a WAP at 10-15W, maybe a switch at 10-15W… Not because of the CPUs, necessarily, but because every CPU every CPU comes with systems to keep the CPU going, keep the power regulated, etc.
Power isn’t from drives, if your OS spins them down (as any NAS solution should).
See my other comment.
You can only spin drives down if they’re idle. If you have a service that touches it - say, homeassistant logging data, tvheadend updating EPG - then they’re going to keep spinning.