Download Prime95 - a handy tool for overclockers and system stability checkers, Prime95 has a feature called "Torture Test" that allows maximum stress testing on the CPU and RAM. There are several options allowing the stress test to focus on the memory, processor, or a balance of both.

Usually Prime95 will detect an error within a matter of minutes if an overclock is not stable, however many people like to let the system "burn-in" overnight to ensure long-term stability. FPrime95 is a small and easy to use application that allows you to find Mersenne Prime numbers. Mersenne numbers can be proved composite (not prime) by either finding a factor or by running a Lucas-Lehmer primality test.

Prime numbers have long fascinated amateur and professional mathematicians. An integer greater than one is called a prime number if its only divisors are one and itself. The first prime numbers are 2, 3, 5, 7, 11, etc. For example, the number 10 is not prime because it is divisible by 2 and 5. A Mersenne prime is a prime of the form 2P-1. The first Mersenne primes are 3, 7, 31, 127, etc. There are only 40 known Mersenne primes. 

There are two ways to use this program. The automatic way uses a central server, which we call the PrimeNet server, to get work to do and report your results. Anyone with Internet access, including AOL, CompuServe, and dial-up ISP users should use this method. You do not need a permanent connection to the Internet. The second method is the manual method. It requires a little more work and monitoring. Recommended for computers with no Internet access or with some kind of firewall problem that prevents the automatic method from working.

New features in prime95.exe

• Throughput benchmarks of all FFT implementations are written to gwnum.txt. These benchmarks will then be used to pick the best FFT implementation to use. This can lead to minor performance improvements.
• Benchmarks are run at 5AM (and every 21 hours after that) for any FFT sizes that will be needed within the next 7 days. Once enough benchmark data is accumulated, these automatic benchmarks no longer take place.
• Default FFT implementations for Ryzen added.
• A few new FFT sizes (up to 50M) are enabled for FMA3-capable CPUs.
• ECM and P-1 on Fermat numbers will automatically add known Fermat factors to the worktodo.txt entries.

Bug fixes

• The Windows version does not use new benchmark data in FFT selection until prime95 is restarted. 
• Throughput benchmarks using less than all cores improperly used all cores. 
• Using benchmark data on AMD Bulldozer with SUM(INPUTS) checking enabled can lead to errors initializing FFTs. Fixed in 29.2 build 5.
• Auto benchmark runs even if user is not running any workers. Auto benchmark runs on battery power even if "run on battery power" option is not selected. 

The benefit of this version is that it is multi-threaded and will automatically manage worker threads to fully stress all cores of your CPU.

Change Info:
1) Support added for AVX-512 FFTs. 2) FMA3 FFTs now have slightly higher FFT crossover points. Soft crossovers are no longer used by default. See undoc.txt. 3) Torture test dialog box options now based on cache sizes. Options for performing a weaker torture test are available. Torture tests that use all RAM are now more stressful. In-place vs. not in-place memory accesses now displayed on screen. 4) Add & subtract operations for AVX-512 FFTs are now multithreaded. This should improve performance for P-1 and ECM when using multiple threads. 5) Benchmark results are now written to results.bench.txt. 6) JSON results are now available for all work performed. JSON results are written to results.json.txt. 7) Default memory available for prime95 changed from 8MB to 1/16th of RAM. 8) PRP tests with Gerbicz error checking are more immune to hardware errors.