Lowest Power CPU & PSU combo for a 6-disk NAS?

[decryption]

I'm looking to build a 6 disk FreeNAS box and wondering what the lowest power consumption CPU & PSU combo is these days? It'll be on 24/7, so I'm looking to cut power usage as much as possible to save money on running costs (electricity is 22c/kWh here in Australia!)

I'm thinking that an Intel Atom D2700 based box will be enough grunt, together with a 4-port SATA HBA - but the motherboards it's bundled with only have PCI slots, not PCIe, which I don't think is enough for a 4-card SATA HBA?

The next option is an AMDE350 based CPU & board, but according to some benchmarks I've seen, it doesn't really use less power than the next option, an Intel i3-2100 CPU. Which costs a little more, but is way faster and I can use an ATX board with more SATA ports.

So really is the i3-2100 the lowest power CPU out there these days, suitable for a 6-disk NAS?

And in regards to a PSU, I've seen the PicoPSU, but it probably doesn't have enough power for 6 drives, does it?

[Renza]

e350 board? http://www.asrock.com/mb/overview.asp?Model=E350M1

has a pcie 4x slot (capable of cards up to 16x) so you could add a HBA in easily