Prime95!

OCCT ("OverClock Checking Tool") is a CPU stability testing program that features :

3C Toolbox is the comprehensive toolbox to save battery, tweak, tune, backup, secure and monitor any Android devices running any ROMs, any kernels.

System Stability Tester - Test your system's stability and performance by calculating millions of digits of Pi.

LinX is a graphical interface for Linpack, a benchmark designed to measure CPU performance. Linpack is also a very useful tool for checking the stability of a CPU. LinX features:› a simple and intuitive interface› max available memory detection and an option to use all available memory› both Intel and AMD CPU support› both 32 and 64-bit Linpack support› Intel HyperThreading support (Pentium 4, Atom, Corei7) and ability to override the number of testing threads› Linpack can be started with different priorities› elapsed, estimated and approximate finish time displaying› ability to test for a specified period of time› optional sound beep on error/successful pass› settings for the last run are remembered› visual indication of testing process to quickly determine possible system hang› monitoring data import from Everest or Speedfan and ability to create graphs for core temperature, fan speed, vcore and +12V voltage› screenshot and graph saving in PNG format› tray icon› command-line keys support to automate testing (run LinX.exe -help for full list)› no additional redistributable packages needed› no installation required (however, there is a version with installer too) »

IntelBurnTest is a program that simplifies the usage of Intel Linpack.

Super PI is a single threaded benchmark that calculates pi to a specific number of digits. It uses the Gauss-Legendre algorithm and is a Windows port of a program used by Yasumasa Kanada in 1995 to compute pi to 232 digits.