Maximum Temperatures for the D3?

So, I've been confused about the maximum temps for the D3 the entire time and wanted to see if you guys know the correct max temps.

Just to recap, In the manual it states that the Maximum Ambient Operating Temperature is 40 degrees Celsius, and that the miner will shut down if the PCB Temp hits 85 degrees Celsius.

Now, I see most people referring to the Chip Temp, not the PCB Temp.  I've been trying to keep my Chip Temp below 85 by downclocking my D3s, but now I'm thinking that it's not necessary.  I've seen where the Chip temp on the S9s is commonly over 100C, and I saw a post which indicated it was from bitmain support that said the S9 chip temp should stay below 115C.

So, should when people refer to Max Temps, should we be referring to the Chip or PCB?

And if bitmain says in the manual to keep PCB under 85C what should we try to keep Chip temps at?

I built some sound reducing boxes (miners in garage), but they increase the temps a little.  Even in the boxes though the PCB temps are in the mid 60s on one D3 (smaller enclosure, 450 clock) with the Chip temps around 80, my other D3 (newer larger enclosure, 500 clock) has PCB in upper 60s, chips in low 70s.  I was worried the temps were too high, but now I'm thinking I should just crank them both up as long as they stay under 80 PCB temp?

Anyone have the official Chip temp max?