Marin Mersenne 2^P-1
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Great Internet Mersenne Prime Search
GIMPS
Finding World Record Primes Since 1996
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Free Mersenne Prime Search Software

Prime95 Version 30.19 build 14

  1. Download Software
  2. CPU Stress Testing
  3. Setup Instructions for New Users
  4. Upgrade Instructions for Existing Users
  5. Software Source Code
  6. Other Available Freeware
  7. Questions and Problems
Any modern personal computer with Windows, Mac OS X, Linux, or FreeBSD can participate. The How it Works page answers many questions you may have before downloading the software. You must also agree to the GIMPS free software license.
Latest version: 30.19 build 14 - see the latest WhatsNew.txt file for a full list of changes. Recent changes include:

Older version history

Highlights of version 30.8 include

  • Huge improvements to stage 2 of P-1 when lots of memory is available.
  • Warning: upgrading in the middle of P-1 stage 2 will restart P-1 stage 2 from scratch

Highlights of version 30.7 include

  • Intel Alder Lake support. Improvements to stage 2 of P-1, ECM. Added P+1 factoring.
  • Warning: upgrading in the middle of P-1 stage 2 will restart P-1 stage 2 from scratch

Highlights of version 30.3 include

  • PRP with proofs. Eliminates the need for lengthy double-checking!!!
  • Resource Limits dialog box to control Prime95's resource usage. See the readme.txt file for setting these options

Highlights of version 29.8 include

  • AVX-512 support
  • Modified torture test dialog box with new options and better understanding of the L1/L2/L3 cache hierarchy
  • More robust implementation of Gerbicz error checking in PRP tests. This replaces LL testing as the default work type

Highlights of version 29.4 include

  • GIMPS has a new sub-project -- finding (probable) prime Mersenne cofactors
  • Like LL tests, PRP tests now support shift counts to aid in running double-checks
  • PRP tests now support a type of low overhead error checking that almost guarantees correct results even on flaky hardware
  • Because PRP tests are highly reliable, we now offer the option to do PRP tests instead of Lucas-Lehmer primality tests
  • For non-base-2 PRP tests, there is a new option to run each iteration twice and rollback if a mismatch occurs

Highlights of version 29.3 include

  • Enhanced error checking for LL tests
  • Faster step 1 GCD for ECM and P-1 factoring

Highlights of version 29.2 include

  • New benchmarking routines to determine the optimal FFT code
  • Changes to default CPU cores assigned to each worker to optimize total throughput per system
  • Optimized FFT sizes for AMD Ryzen
  • The new code will now do multithreaded trial factoring
  • Faster factoring code using FMA if available
  • Improvements to the hyperthread core detection

Setup Instructions for New Users

Joining GIMPS is usually as simple as downloading and running the program, answering a few questions, and the program does the rest.

There are cash awards for discovering a new Mersenne prime!

  1. If you have not done so, create your UserID. It's optional, but required to check your account details, computer status and performance statistics and to assign computers to your user ID.

  2. Download the appropriate free program for your OS (see below for GPU software) and proceed to Step 3:

    Operating SystemVersionReleasedSizeDownloadNotes / Checksums
    Windows: 64-bit30.19b142024-03-308.4MBp95v3019b14.win64.zip
    MD5:    9d4d1c832a64d9b6cb3d8fe5d615acbe
    SHA1:   5b27b418e18b7356f8fc58f3481d268b808f9169
    SHA256: 8012cf0a610f3660aa04a4838c275b4f28b3f373708362c04136e35c5ae885bf
    Windows: 32-bit30.19b142024-03-307.1MBp95v3019b14.win32.zip
    MD5:    b993a0a69844798017bc48dbfbcf8b7f
    SHA1:   414be52c3f575acbce1579b058b019c3cbf4b22e
    SHA256: 8e471649a5c2d33a69835db0aaac2ab2821f96b2318f1b522007e639571d50cf
    Linux: 64-bit30.19b142024-03-305.6MBp95v3019b14.linux64.tar.gz
    MD5:    94d148dbb75d089be699dac97bc7e3d3
    SHA1:   8d7e8a3cc5b1d214daa29f3f3c0da70e06228e93
    SHA256: ccd48d2ceebfe583003dbf8ff1dca8d744e98bf7ed4124e482bd6a3a06eaf507
    Linux: 32-bit30.19b142024-03-304.5MBp95v3019b14.linux32.tar.gz
    MD5:    c3fe9bdfad3037c86dab20db59c52ae9
    SHA1:   4edeea1f365254c40e507aea9c7d6b884bc4108b
    SHA256: 17af605e06b050f93722d11f41b8e55e23ed148bc343288cdd2caa20e022d6f6
    Mac OS X30.19b142024-03-304.3MBp95v3019b14.MacOSX.tar.gz
    Command line version, requires Intel CPU, Mac OS X 10.9 (Mavericks) or later
    MD5:    627d5c8002becafac23da002c7b7e7e9
    SHA1:   8867f3b17daf46337fe5e45bfdc2d3ae26ec9ad0
    SHA256: 520dbf6e6dbd6184626bfae02e8e2d8ba4d4ab081d138a73a3852f08ece1ea6a
    FreeBSD 12: 64-bit30.19b142024-03-305.9MBp95v3019b14.FreeBSD12-64.tar.gz
    Requires FreeBSD 12.0
    MD5:    e9849556939b4cfbe7c3067210381a05
    SHA1:   25e0fe526228d5bce0cfe1935e2966b5d2c9cfec
    SHA256: e000a60499291c35de03aede8fc14d893b2e9d2950e796f540c8a04856c6e1db
    Windows Service: 64-bit30.19b142024-03-306.7MBp95v3019b14.win64.service.zip
    This is for administrators that want the extra security of running a traditional GUI-less service. You will still need to download the standard windows executable to configure the client. This program is for Windows Server experts only.
    MD5:    ff6e4a14850552767c912de3d44c0b45
    SHA1:   0f8b028e50beab9f9c97f38ff43a8074c754df11
    SHA256: d4db4c8d1c26c5e14719c2f40fc31df2e34fdda67aedaa525ace0ea60c09dd39
    Windows Service: 32-bit30.19b142024-03-305.7MBp95v3019b14.win32.service.zip
    This is for administrators that want the extra security of running a traditional GUI-less service. You will still need to download the standard windows executable to configure the client. This program is for Windows Server experts only.
    MD5:    b96a694872cfab2b180784d8ddd3808b
    SHA1:   afef8b88edad1e2025f1e609c95c7fa0d3210f9e
    SHA256: d6a744f5c716700ca6cfbbd37aec410c72ec08acb62bd489da4ceaa432a4f983
    Source code30.19b142024-03-3038.8MBp95v3019b14.source.zip
    for Windows, Linux, FreeBSD, and Mac OS X
    MD5:    e7098647a7be76135a74227ac8e61de1
    SHA1:   4f5f88e7d775c189da95ef1b64c34821d4252def
    SHA256: 49fd8e44d8755a4c05915085b0b15c3589f232cfd539028bbab2c01ffc8ad548

    GPU Software

    If you have a recent discrete videocard powered by an AMD or NVIDIA GPU, it's potentially more powerful than your CPU at prime-testing (or factoring) Mersenne numbers.
    Visit the Mersenne GPU Computing Forum for more information.

    Some Mersenne-related software has been written for NVIDIA and AMD GPUs, including:

    Legacy Operating Systems
    Mac OS X, GUI version29.8b72020-03-195.0MBp95v298b7.MacOSX.tar.gz
    Requires Intel CPU, Mac OS X 10.9 (Mavericks) or later
    MD5:    5a110a0a5210fd10d7b8da0ce9ff43cf
    SHA1:   5a93d5f45dadd09b60520176f9abaead7c22d356
    SHA256: 3a0e228ea35bd96824163c7f5ab8e21502a33ae647752de3e5aab0f88fc7c52e
    Mac OS X
    pre-Mavericks    		27.92012-12-125.1MBp95v279.MacOSX.zip
    Requires Mac OS X 10.3 to 10.8 and an Intel CPU.
    MD5:    0390ae2ff3d4a7082927482d82e62f59
    SHA1:   5f08298fb4aff5dbbab3d072519cd80ecce576c1
    SHA256: c44e3bdae50d3360ec58a0efff47ccfdff5bdc5d31f669e2761da4737d5560d8
    FreeBSD 11+: 64-bit30.7b92021-11-157.1MBp95v307b9.FreeBSD11-64.tar.gz
    Requires FreeBSD 11.0
    MD5:    a88718f5d985c3a0e0f76323969ffcaf
    SHA1:   767e890fb914e5a81b0ee6c0df9b4624408caf4a
    SHA256: 750a36bce52d33db7c6765ea454d12a25aea0b967b99642d3847cb87c7e844a5
    FreeBSD 10: 64-bit28.72015-08-105.3MBp95v287.FreeBSD10-64.tar.gz
    Requires FreeBSD 10.0
    MD5:    5dd21b471946fdcb4858a9fa50fe718b
    SHA1:   5143e7e355f8fdbce5b3629cc9cd8d4e9bd04592
    SHA256: 0a04bb01524e7c10edce501f57e902b3ce9f82cda0e39aaae8bfaa1af95ab416
    FreeBSD 8: 64-bit27.92012-12-124.5MBp95v279.FreeBSD64.tar.gz
    Requires FreeBSD 8.0. May work on later versions.
    MD5:    c6b1c84a79bb1b2e8366a81ddea0087c
    SHA1:   0f2972edb728a017b3bfe7da5cb7fddad7ed785c
    SHA256: 5ab9feddeb53fca9d9684119fae7ac271de3d85a4dd3c3f1fd26ab97ff71c05a
    FreeBSD 7: 32-bit26.62011-04-084.0MBmprime266-FreeBSD.tar.gz
    Requires FreeBSD 7.0. May work on later versions.
    MD5:    d7e78a458b0c7ebbd6db57ff08835739
    SHA1:   b283278dea4887494ebb7357992981ece8df3e08
    SHA256: d4c2c044cfa45311dd7f2c41574f59a0519c989fd6e0ca723505dea12b2ff1fd
    Windows XP: 32-bit29.8b62019-08-185.4MBp95v298b6.win32.zip
    MD5:    4f7d1cc7904d5d9ccb26c8c00b6470a9
    SHA1:   54dd8f9b4692d7a878626ac993562b83cb5587fb
    SHA256: cdd32b4c358869d3f588ae430bc67d9e88a5a69506002f864adac3c477c9202a
    non-x86 OS

    Unix and non-x86 users should check out Ernst Mayer's Mlucas page .

  3. Create a directory and decompress the file you just downloaded. Windows 10, 8, 7, Vista, and XP have built-in unzip features. Other Windows users can choose from a variety of decompression programs. We use 7-zip. Linux and FreeBSD users should use the standard tar and gzip decompression utilities.

  4. Configure Primenet Start the program! Linux and FreeBSD users should run the program from the command line with a -m switch, i.e. ./mprime -m

    Enter your optional userID created on the website in Step 1, and optionally name your computer. We recommend Windows users select Options » Start at Bootup or Start at Logon.

    That's all you need to do! The program contacts a central server called PrimeNet to get some work to do. Usually the program and PrimeNet know the best work to assign, but it's up to you! You can administer your account and computers on your userID's account page. Once you complete a workunit you can track your standings on the competitive stats pages the server updates every hour (see Top Producers in the menu, left, for more stats). You can monitor each of your computers' progress, even remote-control the work assignments they request using your userID's CPUs page!
    Linux and FreeBSD versions can also be set up to run every time you restart your computer.
    Ask for help at the Mersenne Forum.

CPU Stress / Torture Testing

Prime95 has been a popular choice for stress / torture testing a CPU since its introduction, especially with overclockers and system builders. Since the software makes heavy use of the processor's integer and floating point instructions, it feeds the processor a consistent and verifiable workload to test the stability of the CPU and the L1/L2/L3 processor cache. Additionally, it uses all of the cores of a multi-CPU / multi-core system to ensure a high-load stress test environment.

From the most recent "stress.txt" file included in the download:

Today's computers are not perfect. Even brand new systems from major manufacturers can have hidden flaws. If any of several key components such as CPU, memory, cooling, etc. are not up to spec, it can lead to incorrect calculations and/or unexplained system crashes.

Overclocking is the practice of increasing the speed of the CPU and/or memory to make a machine faster at little cost. Typically, overclocking involves pushing a machine past its limits and then backing off just a little bit.

For these reasons, both non-overclockers and overclockers need programs that test the stability of their computers. This is done by running programs that put a heavy load on the computer. Though not originally designed for this purpose, this program is one of a few programs that are excellent at stress testing a computer.

The Prime95 Wikipedia page has an excellent overview on using Prime95 to test your system and ensure it is working properly. The tips presented there should be helpful regarding how long to run the torture test and provide a solid guideline on how long to run the Prime95 stress test.

Performing a stress test is simple:

  1. Download the software and unzip the files to your desired location.
  2. Run the Prime95 executable and select "Just Stress Testing" when asked.
  3. The default options are sufficient to do a well balanced stress test on the system.

Upgrade Instructions for Existing Users

  1. Download the appropriate program for your OS

  2. Upgrade the software. Stop and exit your current version, then install the new version overwriting the previous version. You can upgrade even if you are in the middle of testing an exponent.

  3. Restart the program.

  4. Read WhatsNew.txt

Questions and Problems

Please consult the readme.txt file for possible answers. You can also search for an answer, or ask for help in the GIMPS forums. Otherwise, you will need to address your question to one of the two people who wrote the program. Networking and server problems should be sent to GIMPS admin. Such problems include errors contacting the server, problems with assignments or userids, and errors on the server's statistics page. All other problems and questions should be sent to George Woltman, but please consult the forums first.

Disclaimers

See GIMPS Terms and Conditions. However, please do send bug reports and suggestions for improvements.

Software Source Code

If you use GIMPS source code to find Mersenne primes, you must agree to adhere to the GIMPS free software license agreement. Other than that restriction, you may use this code as you see fit.

The source code for the program is highly optimized Intel assembly language. There are many more-readable FFT algorithms available on the web and in textbooks. The program is also completely non-portable. If you are curious anyway, you can download all the source code (38.8MB). This file includes all the version 30.19b14 source code for Windows, Linux, FreeBSD, and Mac OS X. Last updated: 2024-03-30.

The GIMPS program is very loosely based on C code written by Richard Crandall. Luke Welsh has started a web page that points to Richard Crandall's program and other available source code that you can use to help search for Mersenne primes.

Other available freeware

At this time, Ernst Mayer's Mlucas program is the best choice for non-Intel architectures. Luke Welsh has a web page that points to available source code of mostly historical interest you can use to help search for Mersenne primes.