I’m running an HP Z230 SFF as my little homeserver for the last 5 years. It is not the most powerful, but it was energy-efficient enough, and was doing great for the things I’m running on it, so I kept using it. Recently I noticed that despite being idle, the power usage was higher than normal. Normally the power usage with idle workload oscillates around 25-30W, but it was at nearly 60W.
On Proxmox I didn’t see that any VM was using much CPU, so I dug deeper. In top on the host, I noticed that only one core was maxed out, and the process kworker/1:3+usb_hub_wq was using a lot of CPU.