Over the years, Prime95 has become extremely popular among PC enthusiasts and overclockers as a stability testing utility. It includes a “Torture Test” mode designed specifically for testing PC subsystems for errors in order to help ensure the correct operation of Prime95 on that system. This is important because each iteration of the Lucas-Lehmer depends on the previous one; if one iteration is incorrect, so will be the entire primality test.
The stress-test feature in Prime95 can be configured to better test various components of the computer by changing the fast fourier transform (FFT) size. Three pre-set configurations are available: Small FFTs and In-place FFTs, and Blend. Small and In-place modes primarily test the FPU and the caches of the CPU, whereas the Blend mode tests everything, including the memory.
By selecting Custom, the user can gain further control of the configuration. For example, by selecting 8-8 kB as the FFT size, the program stresses primarily the CPU. By selecting 2048-4096 kB and unchecking the “Run FFTs in-place” checkbox, providing the maximum amount of RAM free in the system, the program tests the memory and the chipset. If the amount of memory to use option is set too high, then the system will start using the paging file and the test will not stress the memory.
On an absolutely stable system, Prime95 would run indefinitely. If an error occurs, at which point the stress test would terminate, this would indicate that the system may be unstable. There is an ongoing debate about terms “stable” and “Prime-stable”, as Prime95 often fails before the system becomes unstable or crashes in any other application. This is because Prime95 is designed to subject the CPU to an incredibly intense workload, and to halt when it encounters even one minor error, whereas most normal applications do not stress the CPU anywhere near as much, and will continue to operate unless they encounter a fatal error.Get Prime95
Developed for non-commercial use, OCCT will not allow you to run it on a computer that is joined to a domain.
OCCT is a Windows application to check the stability. It enables you to test your computer’s stability, using 4 different tests: CPU OCCT and CPU Linpack aimed at testing the CPU, GPU 3D for the GPU stability, and Power Supply a combination of CPU Linpack and GPU 3D to fully load your Power Supply. Each test can be run indefinitely, or for a fixed amount of time. You can even include an idle period at the beginning or at the end of a test, to see how your computer’s temperature rise from an IDLE state to loaded, and the other way round. OCCT also embeds a monitoring engine, giving you readings of the computers inner temperatures, voltages, and fan speed, and displays them in graphs plotted in real-time. OCCT even protects your computer from overheating or damage by including alarms you can customize for every sensor: once you go above (or below) the alarm value for a temperature, voltage, or fan speed, the test will stop to protect your computer.Get OCCT