Is there any way to reduce maximum clock frequency of RK3308 to reduce the heating of CPU?
How to reduce Rock Pi S CPU frequency
Why what temps are you getting?
more than 75 Celsius. Its not only about heating but I also want to reduce power consumption for battery operation.
The original images where @ 1.1
sudo apt-get install device-tree-compiler
dtc -I dtb -O dts -f rk3308-rockpi-s.dtb -o rk3308-rockpi-s.dts
If you go into the /boot/dtb folder you will find all the dtb files there which are binaries.
So to turn then to text which you can edit do the above.
Then convert back to binary so it will boot.
sudo dtc -I dts -O dtb -f rk3308-rockpi-s.dts -o rk3308-rockpi-s.dtb
Think that was the orig image https://dl.radxa.com/rockpis/images/debian/rockpis_debian_buster_minimal_arm64_191029_1055-gpt.img.gz
But have a look in https://dl.radxa.com/rockpis/images/debian/
I am only asking about temps as don’t think I have seen over 55’c @ 1.3ghz but the UK is never very hot 
Then again while back I got x20 raspberry pi heatsinks (little stick on ones, really cheap) and just by habit stick on all socs so maybe that is also having effect.
The early dtb files definately where @ 1.1 ghz and you will find the cpu speed/voltage table in the dtb when coverted to text dts.