Linux

You can run an (emulated) IBM mainframe on it!

Check out BOINC: https://boinc.berkeley.edu/

Raspberry Pi I'm not sure if it's worth it. But in short you can advance some science with spare CPU hours. Should be possible to limit it so it doesn't heat up and use just a bit of the cycles depending on other load...

So I have a smart plug set up on my printer and print server (old HP 4P with separate network print server.

I have NodeRed watching my CUPS queues via HTTP scraping, and if it sees a job in the queue for that printer, it turns on the print server and printer via the smartplug over wifi. I have seen someone link a project that does something similiar.

As a general thing because I found myself trying to justify my Gear Acquisition Syndrome -- it's a good idea to split services across devices, rather than having some monolithic home server (which is where most people start). That way if one box goes down, it doesn't take down your whole stack.

If you have some machines scattered about doing different things, it might be time to consider logically grouping services and splitting them across that hardware.

mine is my reverse proxy, using the nginx proxy manager docker install method

I run a asterisk PJSIP VOIP server on my raspberry pi 5 8GB. I had to use the git and build and recompile and manually load all PJSIP modules because for some reason I couldn't even find an asterisk package on apt db for ARM64 for some fucking reason. Also had to containerize it within a docker because the shit couldn't properly compile without interfering with native system binaries. Shit is so fucking goated and can do PSTN via twilio trunking (call numbers outside of the phone server's number base so basically anyone as long as you make the phone numbers parsed in extensions.conf for each country you wanna call XD). Currently works within LAN but I am planning on making it accessible over the internet using my domain and a tunnel for UDP if possible or just a VPN since my router is being a removed with SIP packets rn. I am having trouble with that part but once it's done I can quite literally ditch any phone plan and use it. Twilio hardly even charges shit for voice rates 🤣🤣🤣. You could also self host your domain + email providing service and then connect that to thunderbird for full schizo-level privacy or sum shit. That's what I do to ditch web-email BS

Skimmed the title. Brain registered words "rpi" and "linux" underneath it. Instant reaction: "Not another app package format please". 😶‍🌫️

I should spend more time reading properly & less time being an old man yelling at tech.

Joplin notes. A really nice notetaking app you can selfhost. Simple enough but stil verry advanced.

irks me that it’s mostly idling

Well it's a small processor and relatively efficient one at that so... how about going the opposite direction? How about measuring the power draw on idle? With other task? I don't actually know if that architecture handles that but I saw some things on the do https://developer.arm.com/documentation/100095/0002/functional-description/power-management/dynamic-power-management?lang=en

Also what about using a RPi Zero instead?

I use my Pi 4B as a DVR for movies and OTA television (MythTV).

There are other tools that handle playback better (OSMC/Kodi, etc) but Myth's configuration and handling of recording schedules is incredibly powerful. Conflict management works well and it can record multiple streams off the same tuner so conflicts are reduced in the first place.