It does have a fan, but it’s silent enough. It comes with a wallmount bracket and fits nicely in my cupboard.
I use it to run openHAB (4.2.1), InfluxDB, eBusd, and Mosquitto. load average: 0.11, 0.06, 0.01, 397 items, 70 things. Using Zwave, Zigbee, and jRuby for all my rules.
Before I used a Odroid XU4, but having more memory made the biggest difference I think.
I started out with a RPi (terrible), upgraded to a small mini pc. To a mirco tower Dell computer with i5 cpu/16GB to a full fledge 2U enterprise server.
I can say moving to a micro tower pc with medocre specs is plenty sufficient to run openhab only. Going balls out on a high end system has no performance increase for automation from what i’ve experienced.
The server i’m running now has 2 sockets 88cores. Its overkill, but i use it for a complete homelab environment with proxmox; OPNsense, openhab, immich, jellyfin, teslamate, frigate, and a ton of docker containers for lots of other personal apps.
If i was just doing openhab a basic computer is sufficient and i ran that way for many years, i slowly expanded out and upgraded not for openhab but to run more services.
It’s extremly quite, i had a 1U supermicro server i was trialing before getting the R730 and that thing was loud as heck, Then got the R730 for the 2U factor and ability to add a lot of SSD’s.
Moving to this 2U allowed a lot better airflow I have the fans ramped down to 2% and you don’t hear it. I’m very impressed with it. My post above shows the CPU’s averaging 45C at that fan speed
