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?
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If you’ve optimized your BIOS settings (balanced mode or power saving wherever possible), the only other option is removing extraneous hardware. All hardware power use (disks, HBAs, other adapters and controllers) adds up. I managed to get idle power consumption of an HP DL-380 G9 down to about 60w (started at 210w) by removing the disks, RAID controller and battery, fiber channel adapters, and extra Ethernet adapter. Each SAS disk I removed saved me 10w. I used one M.2 drive in a PCI adapter instead.
Like you mentioned, these aren’t designed to save power. That Opteron (and the chip set) hales from a time before “performance per watt” was a thing.
I doubt this would fit your use case but wake-on-lan could keep power draw stupid low when nothing’s being used, at the cost of boot time.
What other hardware does it have? HDDs draw a lot, GPU of course, but also each active network interface etc.
It has an HBA, 3 hard drives, and 3 SSDs. I was going to add a couple more hard drives (just to try to get some more use out of old ones I had lying around), but 0.5TB ones might not have enough capacity to be worth their power draw.
Small 2.5" HDDs are quite power efficient, but yes 500mb is kind of the limit where I also start questioning it it is worth to run them.
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
my HBA takes 20W at idle
Even if you could shave off 50% at idle, you’re talking about like $0.10 per day in power savings. Is it really worth spending any time on that?
I mean, at the USA average price of electricity of $0.13 per kWh, then for a halving of 70 Watts, it’s about 11 cents per day, or $40 per year. But at the California average price of $0.35, then the savings is 29 cents per day, or $107 per year.
That’s not small money, especially if it’s free to make these gains by ripping out unneeded functionality. But the point is taken that it’ll be hard to find savings from older hardware, which simply didn’t prioritize energy efficiency.
