Chip's power consumption is <6.6W/Ghs
ATX power loses(82%), DC/DC power loses(87%), Fan(5~20w), etc
So
650W * 0.82 * 0.87 - 20W =
443W, About right.
so an equivalent bfl number would be something like:
60w / .87 / .82 + 2W (fan) + 5W (host) =
91 W (host can be discounted for many since it can run several units)
or "bfl's worst case" 60W * 1.2 = 72W ===> 72w / .87 / .82 + 2W (fan) + 5W (host) =
~108WUnless you want Inaba to eat you alive, never quote that reality, ever again.

By the way, if BFL overclocks, it will raise even that amount by a bit more. Adding the host just raises it further.