Download Prime95 29.8 - 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. Fixed in 29.2 build 3.
• Throughput benchmarks using less than all cores improperly used all cores. Fixed in 29.2 build 4.
• 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. Fixed in 29.2 build 5.

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:
Version 29.4 1) GIMPS has a new sub-project -- finding (probable) prime Mersenne cofactors. This sub-project has two parts: 1) Running PRP tests, and 2) Finding additional factors. To support this new sub-project there are three new work preferences: PRP on Mersenne cofactors, PRP double-checking on Mersenne cofactors, ECM on Mersenne cofactors. 2) Like LL tests, PRP tests now support shift counts to aid in running double-checks. Shift counts are only supported for Mersenne numbers and Mersenne cofactors. 3) PRP tests now support a type of low overhead error checking that almost guarantees correct results even on flaky hardware. We call this Gerbicz error-checking after it was proposed by Robert Gerbicz at mersenneforum.org. This error-check only works for base-2 numbers. 4) Because PRP tests are highly reliable, we now offer the option to do PRP tests instead of Lucas-Lehmer primality tests. There are 3 new work preferences similar to LL work preferences: first-time PRP tests, world record PRP tests, PRP tests on 100 million digit numbers, and PRP double-checking. If you are looking for a 100 million digit prime, PRP testing is recommended rather than LL testing. 5) For non-base-2 PRP tests, there is a new option to run each iteration twice and rollback if a mismatch occurs. Useful only on flaky hardware due to the obvious high overhead. 6) Minor performance tweaks were made to stage 1 of P-1. Save files are incompatible in stage 1. Wait for your P-1 test to reach stage 2 before upgrading.