Set the max frequency of the CPU

cpufreq.sh

#!/bin/bash

# verify your available scaling frequency with:
# `cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies`
# and adapt this script

unset FREQ

case $1 in

        min)
		FREQ=1400000
        ;;

        med)
		FREQ=1700000
        ;;

        max)
		FREQ=1800000
        ;;

        status)
		cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
        ;;

	*)
		echo "Use cpufreq.sh min|med|max|status"
	;;
esac

if ! [ -z ${FREQ+x} ]; then
	for file in /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq;
		do sudo sh -c "echo $FREQ > $file;"
	done
fi