Benchmarks: Power Consumption
Power consumption is kept to reasonable levels for a two-bay NAS, though, reiterating an earlier point, it's a shame the LinkStation 421DE doesn't support idle standby. Having the hard disks spin down when idle would no doubt help save a little more electricity.
Worth noting, also, that while there are no fan control options within the admin panel, the LinkStation kept nice and quiet throughout testing. It isn't silent, particularly with two hard disks installed, but it's far from obtrusive.