Prime95 freeware


Version: 30.3 B6 | Size: 9.90 MB | Filename:
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So what is Prime95, if it’s not a benchmark? Created by George Woltman, Prime95 is a distributed computing project designed to discover new Mersenne prime numbers. It is freeware and available for anyone to download.

If you have a modern PC with Windows, Mac OS X, Linux, or FreeBSD installed, you can participate in the program. Additionally, you will need to have your computer mostly running throughout the day, as well as have internet connection available at least once every two months. Prime95 uses only about 60MB of RAM and 30MB of disk space and sends only several hundreds of bytes every week, so there should be no major impact on the performance of your computer, though it may stress the CPU quite a bit.

You can participate in the program even if you have an older computer. Just keep in mind that the testing may take several months.

If you find a new prime number and are able to confirm your discovery, you become eligible for awards – $1,000 – 5,000 if you discover a number with fewer than 100,000,000 decimal digits, and $50,000 for a prime number with at least 100,000,000. In fact, that $50,000 is a part of Electronic Frontier Foundation’s $150,000 award, which is paid to GIMPS, the developer of the software. $50,000 is retained by the developer for covering expenses, another $50,000 is awarded to a mathematics-related charity, and the rest is awarded to the discoverer of the 100,000,000-digit prime number. Prime95 isn’t so freeware, as it turns out.

However, we would like to stress that Prime95 isn’t a money-making platform. On average, it takes 1-2 years for a new Mersenne prime number to be discovered. So if you thought about making some quick money, you will be disappointed. On the other hand, if you want to help the science of mathematics, why not dedicate your computer to it?

Over the recent years, Prime95 has been highly popular as a stability benchmark among PC enthusiasts and overclockers. Software’s “Torture Test” mode is specifically designed for testing PC subsystem errors to ensure correct operation of Prime95. All in all, the testing features of Prime95 allow you to test a variety of computer components with its preset modes. If you want to go even further, you could select the custom mode and gain more control over the benchmark.

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User Rating: 4.5 (138 votes)


File size:
9.90 MB

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Windows XP, Windows Vista, Windows Vista x64, Windows 7, Windows 7 x64, Windows 8, Windows 8 x64, Windows 10, Windows 10 x64

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Last versions of Prime95
Version Change log
Prime95 30.3 B6 Jan 6, 2021
Prime95 29.8 B6 Aug 19, 2018 Since GPUs are so much better at trial factoring than CPUs, benchmarking no longer times prime95's trial factoring by default. Two new benchmarking options are available: OnlyBenchThroughput and OnlyBenchMaxCPUs. See undoc.txt for details.
Slightly reduced the memory bandwidth requirements for several large FFTs. May lead to a very small speed increase for users testing 100 million digit numbers.
If running more than worker, prime95 looks for any sin/cos data that it can share among the workers. Depending on the FFT sizes you are running, this could lead to a very slight reduction in needed memory bandwidth.
Method for choosing the best FFT implementation changed. In previous versions, the FFT implementation that resulted in the fastest single worker timing was used. In this version the FFT implementation that had the best throughput was selected. For FMA3 FFTs I used a 4-core Skylake to measure best throughput. For AVX FFTs I used a 4-core Sandy Bridge to measure best throughput.
Prime95 29.8 B1 Apr 8, 2019 GIMPS has a new sub-project -- finding (probableprime Mersenne cofactors.
This sub-project has two parts: 1Running PRP tests, and 2Finding
additional factors. To support this new sub-project there are three
new work preferences: PRP on Mersenne cofactors, PRP double-checking on
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30.3 B6

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