Prime95 Version History

This timeline includes only changes that can be verified in the official whatsnew.txt file shipped with Prime95 30.19 build 20. Where a point comes from community sources rather than the changelog, it is labelled as such.

Current release: 30.19 build 20

The current release is Prime95 30.19 build 20 for Windows, Linux and macOS. Example verified checksum, Windows 64-bit package (8,805,545 bytes): SHA-256 d9475f2ff3f4a6a701abc49a86a66126cb48abd10bda6fa87039d98fa8756bca. All four package hashes are listed on the download page. Note that the published source package is build 21, which is not the same as the build 20 binaries.

30.19 (seven documented changes)

1) Edwards ECM curves run about 10% faster than the previous Montgomery curves when plenty of memory is available. 2) ECM stage 2 can now use GMP-ECM resume files, using the worktodo entries ECMSTAGE2 and ECMSTAGE2N, so a GPU can run stage 1 and Prime95 stage 2. 3) A new timestamp option is documented in undoc.txt. 4) The Manual Communication menu choice now also starts proof uploads. 5) Enabling Use Primenet in the Test/Primenet dialog opens the Test/Worker Windows dialog first, so work preferences can be adjusted. 6) P-1 and ECM stage 2 time estimates are calibrated against stage 1 timings for better B2 values. 7) Advanced/Test can now generate PRP worktodo entries for large exponents.

30.18

One documented change: a faster generic modular arithmetic routine, which mainly benefits external programs in the PFGW family rather than Prime95 itself.

29.8

Two changes that still shape everyday use: FFT support for AVX-512, and a Torture Test that sizes its test ranges from the CPU cache size instead of fixed ranges. On machines with more than 5 GB of memory, Blend also began defaulting to using all memory minus 3 GB.

28.3

Support for the Haswell FMA (fused multiply-add) instructions in the FFT code, a significant speed step on CPUs that support FMA.

27.1 and the end of the pre-AVX era

Version 27.1 optimised the 32-bit FFTs for AVX (with the 64-bit AVX optimisation following in 27.3). That is why 26.6 is the last pre-AVX version: everything from 27.1 onward can use AVX code paths on supported CPUs.

26.6

Version 26.6 predates AVX in Prime95. Community guides, notably the Tom’s Hardware Intel Temperature Guide, adopted 26.6 Small FFTs as a heat-testing standard for older Core processors; that is a community practice, not an official GIMPS recommendation. The full story is on the dedicated Prime95 26.6 page.

For the current release and verified hashes, visit the download page. Platform-specific notes are collected in the platforms hub.