Check Raspberry Pi CPU Temperature:
A light-moderate use Raspberry Pi 2 in an office environment measures in the 40 - 45 C range (no fan, small heatsink, with case).
A red thermometer icon superimposed on the Raspberry Pi display output means the Raspberry Pi is overheating and is throttling the CPU and GPU to avoid self-destruction.
|CPU temperature [C]||icon||throttle|
|80 - 85||CPU|
|> 85||CPU & GPU|
The current Raspberry Pi CPU speed (actual speed, not limits or requested speed) is obtained from
vcgencmd measure_clock arm
The output is in units of Hertz:
The Raspberry Pi 2 and 3 clock speed is dynamic:
|CPU use||clock speed [MHz]|
|idle||600 (Raspi 2 and 3)|
|100% one or more cores||1200 (Raspi 3) 900 (Raspi 2)|
Log temperature and clock speed
You can use
crontab -e for setting a schedule to periodically log temperature and CPU frequency.