SYS Informer - Computer diagnostics, hardware monitoring, network audit, and benchmarking.

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.

Udev Discover - A helping tool for udev testers, coders, hackers and consumers.

Bginfo - This fully-configurable program automatically generates desktop backgrounds that include important information about the system.