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.