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SPECIFICTION
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Prime95

mersenne.org

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Spec score 7.6 #13 of 26 in Hardware Diagnostic Software

What it is

Prime95 is free Mersenne-prime search software for people who want to contribute computing work to GIMPS. It can also put a sustained workload across CPU cores to check processor and L1, L2, and L3 cache stability. For project tasks, Prime95 contacts PrimeNet for work; users can monitor computer progress and manage assignments remotely through the account’s CPUs page. Listed work includes PRP and Lucas-Lehmer tests, P-1 and ECM factoring, and trial factoring. Downloads include Windows, Linux, Mac OS X command-line, and FreeBSD builds. Administrators can choose a GUI-less Windows service build, which is intended for Windows Server experts. The source archive covers Windows, Linux, FreeBSD, and Mac OS X, though the code is described as non-portable. Version 30.3 introduced a dialog for limiting resource use. GIMPS participation is free and open internationally. The license permits indefinite free use on computers users own or are authorized to use, and provides the software as-is without warranty.

Spec sheet

Purpose
Prime95 is free Mersenne prime search software used to participate in GIMPS.Read 7 Oct 2026 · mersenne.org
Privacy
GIMPS says it will not sell, distribute, or release participants’ email addresses or other supplied information except where required by law.Read 7 Oct 2026 · mersenne.org
Support
The download page directs users to the Mersenne Forum for help and lists email contacts for networking/server issues and other software questions.Read 7 Oct 2026 · mersenne.org
Founded
1996Read 28 Sep 2026 · mersenne.org
Maker
Mersenne Research, Inc. owns and operates Mersenne.org and is described as a California nonprofit organized for mathematical and computer science research and related education.Read 7 Oct 2026 · mersenne.org
Hardware support
The page says recent NVIDIA or AMD discrete GPUs may be more powerful than a CPU for prime testing or factoring, with separate GPU programs communicating with PrimeNet through AutoPrimeNet.Read 7 Oct 2026 · mersenne.org
License and warranty
The EULA allows indefinite free use on computers owned by the user or where they have permission, and provides the software and information as is without warranty.Read 7 Oct 2026 · mersenne.org
Participation
GIMPS participation is free of charge and open to the public internationally.Read 7 Oct 2026 · mersenne.org
PrimeNet coordination
The program contacts PrimeNet to receive work, and users can view computer progress and remotely control work assignments from the account CPUs page.Read 7 Oct 2026 · mersenne.org
Resource controls
Version 30.3 introduced a Resource Limits dialog to control Prime95 resource usage.Read 7 Oct 2026 · mersenne.org
Source code
The source archive is listed for Windows, Linux, FreeBSD, and Mac OS X, and the page describes the code as highly optimized Intel assembly and completely non-portable.Read 7 Oct 2026 · mersenne.org
Stress testing
Prime95 runs a heavy, consistent workload across CPU cores to test CPU and L1/L2/L3 cache stability.Read 7 Oct 2026 · mersenne.org
Supported downloads
The current download page lists Windows, Linux, Mac OS X command-line, and FreeBSD builds.Read 7 Oct 2026 · mersenne.org
Test types
The download page lists PRP tests, Lucas-Lehmer tests, P-1 and ECM factoring, and trial factoring among its project work and software features.Read 7 Oct 2026 · mersenne.org
Windows service
A GUI-less Windows service build is available for administrators, and the page says it is for Windows Server experts only.Read 7 Oct 2026 · mersenne.org

Plans and prices

Prime95 Free Free to download and use indefinitely on computers you own or are authorized to use · participation is free of charge Read 7 Oct 2026 · mersenne.org

Every Prime95 plan and price →

Strong points and limits

Strong points

  • Free use indefinitely on authorized computers
  • Checks CPU and L1/L2/L3 cache stability
  • Remote assignment management through PrimeNet
  • Resource Limits dialog controls usage

Limits

  • Software is provided without warranty
  • Source code is described as non-portable
  • Windows service build is for Server experts

Who it suits

Prime95 suits people interested in contributing computing work to GIMPS or checking CPU and cache stability. Its Windows service build is aimed at Windows Server experts.

Verdict

Prime95 combines public prime-search participation with a sustained CPU and cache workload. Its use is free, but the source is non-portable and the software comes without warranty.

Where Specifiction places it

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