I'm new to selfhosting and I find myself rarely using the server, only when I need to retrieve a document or something.
I was thinking of implementing something to make it power on, on demand, but I'm not sure if this might be harmful for the HDDs, and I'm not sure how to implment it if so.
What's your recommendation to do so? I'm running a dell optiplex 3050
I'd question that. I have three 3080 and they're consistently about 8W each with one ssd and onboard graphics. I even went so far to splice three barrel jacks to a single 60w power supply that powers all three to avoid the losses of an additional 2 power supplies and this gets me the 8w idle power with Debian and throttling.
I have the micro form factor I assume the same as you. Basically just a laptop in a small desktop case. I never installed tlp I'll have to give that a shot but I'm pretty sure it's optimized. I have two as servers and one as a router and I'd love to get it down to 12w total! I monitor the whole server rack with an iotawatt and all my servers and networking gear hovers around 75w idle.