I also recently started the journey of reducing the idle power usage of my NAS/server. I find that the power usage during the day with Transmission running is around 50W. In the evening I shut down Transmission, allowing my 3 active drives to go idle and sleep, reducing the power to around 38W. My cores are reacing ~C7 and full package around C2.
Yesterday I did some more experiments with my 10GBe NIC. I removed all drives, booted Unraid and measured the power usage. I then removed the NIC, booted Unraid and found that the power usage dropped by 15W! It's an old Dell Broadcom 57810S Dual-Port 10GBASE-T Converged Network Adapter, modded with two 40mm Noctua fans for cooling. So I'm thinking about swapping that out. I saw that @mgutt was using an Intel X550-T1 10GbE (also using RJ45 connection, same as I have). I might be able to get one second-hand for around €120, so if it can save me at least ~8W, it should pay back in a few years, also allowing me to run without fans, which is nice. Do you think that will reduce average load significantly?
Another thing is that even without my PCIe NIC, MB network disabled, no hard drives, my NAS still pulls around 15W from the wall. The specs are:
Gigabyte Technology Co., Ltd. B560M DS3H V
Intel® Core™ i3-10105 CPU running stock settings
32 GiB DDR4, I'll need to check the brand
Samsung 980 1TB NVME
~300W 80 Bronze PSU, I think Corsair, but I'd need to check. It's ~10 years old.
4x 18TB WD Ultrastar DC HC550, 7200RPM
2x4TB WD Red Plus, 99% of the time spun down
I already followed the guide. Most motherboard settings are set to power saving. Turbo boost disabled, max sleep state set to S10. Onboard audio disabled, aggressive power management options all on. I do notice that the heatsink on the motherboard can become quite warm to the touch, even when fully idle. It's the heat sink labeled UD in this picture. Any more suggestions, things I can try, components I could swap?