@Salvador Liébana: Please don't use 1.5 Volts. You will destroy your Rockpro64! If your CPU can't handle 2.2GHz at 1.3 Volt then it can't handle it at all. 1.5 Volts is .25 Volts above the RK3399 specifications. 1.5 Volt will not only wear your CPU much more than needed it will also make the system unstable. Run 'stress -c 6' and you will see.