The numbers VERY much look unconventional, they total system power consumption on TPU is higher to start with and lower to finish. They need 1.25v to hit the same kind of clocks this Romanian site hit with 1.4v.
Increasing the voltage from 1.25 to 1.4v has a MUCH higher impact than raising voltage from 1.1 to 1.25v. That TPU image absolutely contradicts the Romanian's sites findings and directly says they are BS which is what they look like.
Romanian site says 380W stock 620W or something over volted, card only. TPU says SYSTEM goes from about 430W to 600W.
As power increases exponentially with voltage, 1.25-1.4 increases power a great deal more than 1.1-1.25v, as such I would expect a card needing 1.4V to increase in power more, but why on earth they would need 1.4v to hit a low overclock no other reviews show the card needing says that in itself is where the problem is. They've just whacked voltage up to max for no reason and seen how high it can clock, regardless of the fact that they could do that clock for much less.
Like I said, you could put a 900Mhz core to 1.5v and probably double wattage for no performance gain... it's just stupid.