But either way, they are either selling a faulty product knowing that their customers are unlikely to even reach ROI, which is all kinds of wrong. Or they are selling second hand equipment from their own mine despite the law.
IMHO it is your first one: To squeeze out the highest possible yield of the 16nm chips Bitmain has seriously widened the QA window for what are "usable" vs good vs Prime chips.
Looking at speed/hash rate spread between boards I'd guess at least 3 levels are used for binning chips to be used when populating boards targeted for highest efficiency miners (s9/R4). Hopefully humorous example would be 'meh', good to very good, and finally best. Given the typ yield of 16nm that makes for probably 2-3x more 'meh' to good (say >80% of cores work) chips than best (>90% cores work
at full speed) grade so....
Tie that with lapses in board assembly quality checks... On the 2 s9 boards I had fail the placement and soldering of the VRM was -- horrible. Frankly, surprised it passed at all considering the module was rotated enough to be just literally a hair breadth away from shorting right off the bat. How/why that wasn't caught by an inspection camera, who knows...
With the T9 hopefully their sacrificing eff by pushing the Vcore higher is what results in otherwise 'good' grade chips performing as very-good or better. As to the board assembly - who knows...
Your assessment is plausible, and if its true, then Bitmain has turned into the MacDonald's of the Crypto industry, willing to sacrifice quality for profit. I'm sure they will start to feel the results of this approach soon if they keep it up. I guess time will tell how their T9's go, but I for sure will not be doing any more business with them.