A couple of years ago I bought a second hand HP desktop with Intel Core 2 Duo. I've been running it 24/7 and it's serving as e.g. PiHole DNS server and I'm running some cron jobs. I've never really considered the power usage, but I just did some calculations and it surprised me a lot how much power it would use.
This website mentions an idle power usage of 50w, and load power usage of 100w. Based on 95% idle, 5% load, I come to about 1200 kWh per year.
For a RPI 4b, the power usage is apparently 3w idle, 7w on load. Total power usage would be only 83kWh!
We currently pay about $0.30 + GST for power, so my current PC costs me $440 per year to run, and the RPI only $29?
Is my calculation correct or did I miss something? For that difference I can buy almost 3 new RPI's...