Now running Proxmox with some Minecraft servers, several programming projects, telegram bots, VMs for friends, android building, storage and similiar.
Consuming around 300W in average load (this is Italy, and I pay around 0.29€/kwh), most of the hardware comes for free decommissioned from businessess, or for cheap from charity shops. I exchanged my old Intel Core 3rd gen machines because they only had 2 slots of DDR3 non-ECC RAM and I needed at least 32GB per machine.
HP Z420:
CPU: Intel Xeon E5-1620 (8) @ 3.800GHz
GPU: NVIDIA Quadro 410
Memory: 15736MiB / 39911MiB
HP Z800:
CPU: Intel Xeon X5660 (12) @ 2.794GHz
GPU: NVIDIA GeForce 210
Memory: 11772MiB / 48150MiB
https://browser.geekbench.com/v6/cpu/3439729
https://browser.geekbench.com/v6/cpu/3439726
This is a small closet room inside my bedroom. You can't really hear the sound from outside, so I set the fans to max power. It's less than 1.5 meters tall, so it's really hard working inside. Everything that can be done remotely is done remotely.
I have a symmetrical 1G/1G fiber connection (29.99€/mo)