"Despite voltage being lower than expected (barely touches 1V), the cards somehow draw more than 400 amps."
Someone needs to go back to basic electronics class. The N31 chip itself drawing 400A is no big deal, why do you think the VRM section of today's cards often have a dozen or so 70-90A "power stages"? That doesn't mean the card is drawing 400A from the PSU, as the supply is at 12V not 1V, so more like 30-35A (which is easily supplied by pretty much ANY modern PSU's 12V "rails").
That's also complete BS the launch window for N31 was missed by a year. 6 months BEFORE 6950xt, and barely a year after N21? Come on....