I have a lenovo g510 with intel i7-4700 inside and after several months something strange has happend. When it runs using battery power everything is ok - cpu freq is scaling. But when it's plugged in then cpu feq is always about 800MHz.
lscpu
Model: 60
Model name: Intel(R) Core(TM) i7-4700MQ CPU @ 2.40GHz
Wersja: 3
CPU MHz: 800.156
CPU max MHz: 3400,0000
CPU min MHz: 800,0000
BogoMIPS: 4789.02
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
intel_pstate
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave
I have also Windows on this laptop and situation is the same on both OS. I'm not using original charger but with the same parameter as original one.