I recently was told that the only difference in all these different "S" models is that when the Chip orders arrive, Bitmain tests them. The most efficient chips from the foundry are assembled into the "Pro" units and the less efficient chips are earmarked for the T's and E's and etc etc. I don't pretend to know about "chip quality" or manufacturing processes. How plausible does this sound to someone who knows this space?
this is exactly how it works, some chips from the die's will have near perfect traces and have the ability to keep a constant temp at a certain frequency
the under performers will heat up under the same settings , so those chips need to be set to run at a lower freq to achieve adequate cooling so as not to
over heat and destroy the chips, just like the s9's the 13.5 units have an average 600 set on freq, the s9i's have 650 so each board running 50hz faster
will yield that .5-1 th +
this is some what common in chip manufacturing , in my years building computes you will see some of Intel's chips not do as good in the benchmark tests and
those same chips would always be hotter compared to the cream of the crop
