CPU-Z - CPU-Z is a freeware that gathers information on some of the main devices of your system : Processor name and number, codename, process, package, cache levels.
Speccy - Speccy - find the details of your computer's specs. Great for spotting issues or finding compatible upgrades. Download the latest version free.
Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Neofetch - Fancier version of Screenfetch that displays colors and supports more platforms.
HWMonitor - HWMonitor is a hardware monitoring program that reads PC systems main health sensors : voltages, temperatures, fans speed.
Cinebench - CINEBENCH is a real-world test suite that evaluates your computer's performance capabilities.