ComfilePi B seres (CPi-Bxxx) has a larger heatsink.
Throttling protects the device from overheating by reducing the CPU's frequency.
The Raspberry Pi goes to throttling mode over 85 degrees Celsius.
I tested using an aging test program on the CPi-Bxx model.
CPU temperature is 69.3 degrees Celsius.
I measure this using multimeter.
The temperature at the back of the device is 50.3 degrees Celsius.
The CPi-Bxxx series doesn't go to throttling mode.