An "Avalon unit" includes every component in the box with fans. The contents of that box are irrelevant. If they say it uses 450W, and it uses 620W, then they are fucking liars. Plain and simple. "It's the power supply" is no more relevant than "it's the ASICs". The simple fact is that the shipped unit does not work as described.
But there is a simple explanation, they did not calculate in the phase angle between the current and voltage :-)
http://en.wikipedia.org/wiki/Power_factorYou need to multiply the marketing power consumption with 1.378 to end up with the real numbers :-)
(Yes I am joking)
Anyways, the supporting electronics like the motherboard, the PDU, fans and power supply itself will not use more than just a handfull of watts, more like 30 or 40 watts.
Don't forget that Jeff measured power consumption with the UPS included, our APC Matrix 3000 uses about 120 Watts to keep it's batteries afloat and run the electronics.