Six years with a fanless server
There is a particular kind of small server that never shows up in benchmarks: a fanless box with two NICs, a few gigabytes of RAM and no moving parts, sitting on a shelf doing DNS, a wiki and a git remote. I have run one for six years. Here is what has been true the whole time.
Idle power is the spec that matters
The box draws about six watts. That is a rounding error on the electricity bill and, more importantly, it means no fan, which means no dust, which means no maintenance. Peak performance has never once been the constraint.
Storage is where the money goes
The first SSD died at year three with no warning. The replacement is a slightly boring, slightly overpriced drive with power-loss protection, mirrored to a second one. Everything else in the machine has been cheaper than the disks.
The software churns, the box doesn't
Over six years the operating system was reinstalled twice, the services moved from hand-written units to containers and partly back again, and the reverse proxy changed three times. The hardware was touched once, to swap that SSD. If you're deciding what to spend attention on, that ratio is instructive.
What I would change
Buy the version with ECC memory. I didn't, and the one unexplained kernel panic I've had will remain unexplained forever.