I have a Proxmox server running two Opteron 6272 CPUs on an Asus KGPE-D16 (chosen because it was the fastest computer that supported Libreboot, although I haven’t gotten around to installing it). Using normal BIOS settings, it’s drawing just under 100W at idle, measured via smart plug reported in Home Assistant. With aggressive efficiency settings (PowerCap to P-state 4 and disabling CPU 2 entirely) it idles at 70W. It’s a server, not a gaming PC, so it doesn’t appear to have any options for underclocking or adjusting voltage.
Anybody know of any other ways (maybe software-based) to get the power draw down further?
If you don’t mind the downtime, I’d turn it off, disconnect hba and all but the boot disk and boot up to see how much power they take. HBA can take a lot. You could also consider spinning down your HDD if they don’t need them that often