µMPX doesn't decide whether or not the CPU is throttled, this is a decision made by the OS (I'm guessing you're running Raspbian). You would see the same thing when running the command
Code:
vcgencmd get_throttled
in the terminal. You seem to have hit the "soft" limit (at 60 degrees C) which does not do as much throttling as the "hard" limit (85). If you don't see this on your other pi's, they must be cooler than this one
or are running an older Raspbian version which does not have the same throttling thresholds
or are not 3B+ models but 3B's.
See this link for more info:
https://www.raspberrypi.org/documentati ... agement.md