a quien pueda interesar... estos son los modos de overclock para meterlos en el config.txt
Normal
force_turbo=0
arm_freq=700
core_freq=250
sdram_freq=400
over_voltage=0
Modest
force_turbo=0
arm_freq=800
core_freq=300
sdram_freq=400
over_voltage=0
Medium
force_turbo=0
arm_freq=900
core_freq=333
sdram_freq=450
over_voltage=2
High
force_turbo=0
arm_freq=950
core_freq=450
sdram_freq=450
over_voltage=6
Turbo
turbo_mode=0
arm_freq=1000
core_freq=500
sdram_freq=500
over_voltage=6