What's too hot for these to run at? I'm measuring about ~58*C at the heatsink. Don't really know how to safely get a measurement at the chip.
The datasheet says chip max tolerance 125ºC, but practically 70ºC is crazy hot and past 80ºC is too hot.
hmmm, you mean measured at the chip or at the sink? If at the sink, I would agree. 70-80C at the chip should be just fine.
S9 has two temp and it seems to tolerate second temp up to 110-113C. Best info was in Spondoolies, where they gave you on-chip temp that was tied up to the system. Readout of up to 115C was fine, at 120C throttling began.
At the heatsick. I believe sidehack is working on an overtemp shutoff at about 80ºC for the pod/terminus.