While Thunderbolt's original spec stated that 10W is available to bus-powered devices, the internal SSD is left short-changed by the high power requirements of the essential supporting electronics.

(An Intel spokesman, Jason Ziller, Intel Director of Thunderbolt Marketing, told us that the Thunderbolt bus has been revised to allow up to 12W of power, although Thunderbolt devices are still currently limited to drawing 10W maximum.)

For a start, the Thunderbolt cable itself consumes several watts; the latter cable is an active transmission-line device, with two power-hungry chips hidden inside the plugs on each end.

So while Thunderbolt may deliver up to 10W of power, only 3.5W is available for the SSD, as Elgato warns in the label inside the case. We did try a SATA 6Gbps SSD though, and discovered why Elgato did not fit the same.