> I'm talking about something with an ARM CPU,

Why? There is no evidence that ARM is the only power efficient CPU. i5, i3 and n100 are all power efficient.

> no video, no audio

Why? Disable onboard video if you care that much.

> lots of memory (or SODIMM slot) and 10+ SATA ports This eats power, conflicting with the rest of your requests.

> Sure, anyone can buy a self-powered USB3 hub and add 7 external HDDs to a raspbery, but that level of performance is really really low, not to mention the USB random disconnects. And no, port replicators aren't much better.

No, that's not what you do for a power efficient NAS. You build an i3, i5 or n100, turn off all unneeded peripherals, and configure bios as needed to your level of desired power consumption. under 10W is achievable.

> Why? There is no evidence that ARM is the only power efficient CPU. i5, i3 and n100 are all power efficient.

They are, but the motherboard is not, or at least not as much as an ARM board.

> Why? Disable onboard video if you care that much.

And it would boot... how? AFAIK, no UEFI system is capable of booting headless and very very few BIOS systems were.

> No, that's not what you do for a power efficient NAS. You build an i3, i5 or n100, turn off all unneeded peripherals, and configure bios as needed to your level of desired power consumption. under 10W is achievable.

I very much doubt that. N100 maybe, just maybe, could go lower than 20W if the power source is very very efficient, but I haven't seen any system with 10+ SATA ports. The commonly suggested solution here, to add a server SAS/SATA controller, would double or triple the idle power.