Prime95

Prime numbers are natural numbers other than 1 that only divide by themselves and the number 1. There are a few mathematical methods to prove the primality of numbers and as of 2011, the largest of them and has approximately thirteen million digits.
The fact that the last world records where calculated within the GIMPS (Great Internet Mersenne Prime Search) network makes all of them Mersenne prime numbers (a positive integer equal to 1 less the power of 2).
Prime95 is the Windows version of the application serving as a client for the GIMPS project. Putting aside the prize and the money involved in finding a new Mersenne number, the application can also deliver a great environment for system stability tests.
Mathematics is the basis of a CPU and that is what they do all day long. Thus, Prime95 can prove to be the perfect tool for checking out both performance and steadiness.

Comparison with other similar apps

The program's processor stressing capabilities makes it one of the top choices of overclocking enthusiasts when it comes to testing out their new PC configurations. While considered the best in its category by many users, the alternatives comprise Orthos, CPU Free BenchMark, CPU Burn-in or IntelBurnTest.

Torture Test

Prime95 features a `Torture Test` that puts your CPU and RAM to the test primarily for guaranteeing the correct execution of the application on that particular PC. It comes in three variations, from `Small FFTs` to `In-place large FFTs` as well as the cruel `Blend` mode that generates the maximum stress for your system. One thing you have to take into consideration is that you need during the operation is, at all times, a monitoring tool for your computer's temperatures.

Performance

The successful pass of the `Torture Test` ensures you of one rock solid computer configuration. The recommended number of hours that you should run this test, if sure of your system's stability, is twenty-four. Beware that your processor will produce a great deal of heat and may even break down due to the extreme FPU (floating point units) utilization. Additionally, Prime95 also provides a benchmark for your CPU that you can run and compare your results within the community.

Powerful  and efficient software

This combined Mersenne prime finder / system stability tester software is responsible for many things – from aiding the GIMPS network in finding new prime numbers to frying CPUs. Nevertheless, Prime95 is the real deal when it comes to both aspects of its goals; use it wisely though – look out for temperatures when running its tests and you will get your answer whether you own a fully-stable rig or not.