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 30.7 build 9

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: 30.7 build 9 - see the latest WhatsNew.txt file for a full list of changes. Recent changes include:

Older version history

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-bit30.7b92021-11-159.9MBp95v307b9.win64.zip
    MD5:    174f03c7505a77d639600bfc6df79617
    SHA1:   0bd23035fce5ddfefdb196dc2eb64cea8290cf4d
    SHA256: 119480c2910cd4fe6aee6b408bc24a063b33f444d92cfefd70af5d85f58a645d
    Windows: 32-bit30.7b92021-11-158.4MBp95v307b9.win32.zip
    MD5:    986e31da9b991a35efe30b19c3370704
    SHA1:   c15fd836f85d8779015b4aa1b8d6a0ad9d3f1f34
    SHA256: 6747bca84d089b803aebe3428a2506a613177dd106de5e9415135ffcb601433a
    Linux: 64-bit30.7b92021-11-156.8MBp95v307b9.linux64.tar.gz
    MD5:    053e3f8afdb8275345cfbe94207612da
    SHA1:   f57bcc5c5d7403a4a7ee0d32abab01d8da114ed8
    SHA256: d47d766c734d1cca4521cf7b37c1fe351c2cf1fbe5b7c70c457061a897a5a380
    Linux: 32-bit30.7b92021-11-155.7MBp95v307b9.linux32.tar.gz
    MD5:    6537e79e3495e9cf0921f81e28ef9f52
    SHA1:   d5ab3a1cc1ae2c320f64295a22ec2b44ba290be2
    SHA256: 3ff40a24632c56d5bcf15c0ebc41a34cd025c0c9a3dc1c6550db92b21c1e806f
    Mac OS X29.8b72020-03-195.0MBp95v298b7.MacOSX.tar.gz
    Requires Intel CPU, Mac OS X 10.9 (Mavericks) or later
    MD5:    5a110a0a5210fd10d7b8da0ce9ff43cf
    SHA1:   5a93d5f45dadd09b60520176f9abaead7c22d356
    SHA256: 3a0e228ea35bd96824163c7f5ab8e21502a33ae647752de3e5aab0f88fc7c52e
    Mac OS X
    command line version
    29.8b72020-03-194.5MBp95v298b7.MacOSX.noGUI.tar.gz
    No GUI. Requires Intel CPU, Mac OS X 10.7 or later.
    MD5:    9b6920d933d3c70eadd5a0942088881c
    SHA1:   7a20a100697c2c545db2f45c7973378d46875ccb
    SHA256: d0b4e447f67249dd5483dc1afc883e535c69632787eb70e9f42e9c15fed04a26
    FreeBSD 11+: 64-bit30.7b92021-11-157.1MBp95v307b9.FreeBSD11-64.tar.gz
    Requires FreeBSD 11.0
    MD5:    a88718f5d985c3a0e0f76323969ffcaf
    SHA1:   767e890fb914e5a81b0ee6c0df9b4624408caf4a
    SHA256: 750a36bce52d33db7c6765ea454d12a25aea0b967b99642d3847cb87c7e844a5
    Windows Service: 64-bit30.7b92021-11-158.2MBp95v307b9.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:    ac51f8e7d6825ff7062ab8fd8375b09f
    SHA1:   83601ceaa36ba8bc409bbe74d37c0de161db32ea
    SHA256: d1cfdaaaf2094ace93672dbb77aa2d5409849d812cdb64fef8d05bf5ebdaa6de
    Windows Service: 32-bit30.7b92021-11-157.0MBp95v307b9.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:    abc3d048c91f588264420dd4de5c464d
    SHA1:   9dd735fd6b9a0074408fcdfd95bda14a2be35769
    SHA256: 6e50ca83cbe15a8f13688fee8b6b2c12c754ffefc7d7c068af3e76908534a4a1
    Source code30.7b92021-11-1548.6MBp95v307b9.source.zip
    for Windows, Linux, FreeBSD, and Mac OS X
    MD5:    407b2883f2e10d05ce5c127402cc4d10
    SHA1:   37542b66fb2d3fdb8903ab07602a8009b0cb628d
    SHA256: e89ce78b01eb3055f5503eabd9d0aec95e1e832361f3f2987098969fe649fdb5

    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
    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 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 (48.6MB). This file includes all the version 30.7b9 source code for Windows, Linux, FreeBSD, and Mac OS X. Last updated: 2021-11-15.

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.