I received my $90 ASRock B660M PRO RS today. Time for sharing some results.
TL;DR: 45 watt idle with (LSI HBA + 4 x 3.5" spundown + 2 x NVME + powertop auto + ‘powersave’ scaling governor). This is the lowest idle I have been able to achieve so the board is a keeper!
By returning the 2nd best board tested B660M-PLUS WIFI D4 I am giving up the 2.5GB NIC and the PCIe 5.0 slot. But also that board is almost twice the cost ($90 vs. $160). I will likely build a new NAS server in 2 years when PCIe 5.0 is more mainstream so I rather take the power savings now and get what I really need.
Snapshot of my testing spreadsheet to help folks. I did not record some of my earlier test attempts with other boards.
