So this pdf on the mango SOM used in AXT1800 mentions the temp range for the commercial boards (which I assume this is) is 0-65C.
The gl_fan app only polls the temp and sets the fan every 20 seconds, so If you have a large load spike I suggest bumping the integral -i and derivative -d values of the PID loop as it will not have very many readings to work with to ramp up or smoothly change the speed. In other words- If the load spikes you want the fan to come up to speed quickly. If you only set the temp to 60, the default -i and -d values will never let the fan adjust fast enough to hit the target temp - it will constantly undershoot one way or the other keeping the fan from ramping up because of the slow poll rate.
These settings work fairly well for me to keep it from hitting 65.
uci set glfan.@globals[0].temperature='60'
uci set glfan.@globals[0].integration='4'
uci set glfan.@globals[0].differential='20'
uci commit glfan
/etc/init.d/gl_fan restart
you can test this yourself without setting the above
/etc/init.d/gl_fan stop
gl_fan -v -t 60 -i 4 -d 20
It will give a temp output and how its adjusting the fan - to get the fan speed use gl_fan -s in another terminal.
Also the heatsink itself does a good job (it should as its most of the weight of the unit), without the fan and running full load on the 4 cores and using the wifi It doesn’t get above 66.