Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Core Temp - Nov 4, 2017 - Core Temp is a compact, no fuss, small footprint, yet powerful program to monitor processor temperature and other vital information.
GPU-Z - GPU-Z is a lightweight system utility designed to provide vital information about your video card...
iStat Menus - "An advanced Mac system monitor for your menubar."
Real Temp - Real Temp is a temperature monitoring program designed for all Intel single Core, Dual Core, Quad...
HWMonitor - HWMonitor is a hardware monitoring program that reads PC systems main health sensors : voltages, temperatures, fans speed.