My new worthless prediction (I'm batting .000, lol)...
There is some very compelling evidence that supports this hypothesis. But the most glaringly obvious is the single PCI power connector. They're not so stupid to design it to handle 420w. But they were compelled to squeeze as much hash out of each chip that they threw away common sense.
Remember "under promise, over deliver"? Yeah, not to so much anymore. The new motto... "We deliver dangerous crap because we're cheap bastards."
1 month ago (after I saw the picture of the PCB with only one 6-pin power connector)
I wrote an alarming email to Sam directly. Sam replied within one hour, and replied he would discuss the issue with the developers.
My guess is that they have added a second power-connector (on the opposite side, so you cannot see it on the box photos), or.... they calculated that one connector was still appropriate, which would mean that only 200 to 250 watt is used per PCB. If this last is the case then they have a rabbit-in-the-hat : one box gives 600 Ghs running 250 Watt gives 0.41 W/Ghs............
But my fear is that they didn't either add a connector nor have a 0.41 W/Gs.....