.... But I would also expect the symptoms you describe with an overheat, and I'm not seeing them. No increasing temps, no "x"s on the chips, HW errors still negligible. Fan speeds are dropping, now 1800-1900, down from 2200-2300. So the unit is getting cooler as it slows down. .... ...
There, my friend, is the sign you are looking for!
Fan speeds dropping ... unit is getting coolerThat means there are some chips that have gone offline!
EDIT: Either that, or the chips are not getting work ..... now you see how that the queue argument was formented in my mind?