Prime95 30.19 Build 20: What Changed in This Release
Bottom line first: Prime95 30.19 build 20 is a focused maintenance and GIMPS-work release, not a Torture Test overhaul. Its official change list, in the whatsnew.txt file included with the program, contains seven items, centred on ECM factoring work, a new documentation-file option, communication behaviour and small interface improvements. Nothing in the release changes the Torture Test presets, their definitions or the official duration guidance. If you stress test with 30.18 today, upgrading is simple and low-risk; if you do ECM work for GIMPS, two of the seven items speak directly to you. The complete version record is kept on our version history page.
Prime95 is a freeware program by George Woltman for GIMPS, the Great Internet Mersenne Prime Search. A note on sources before the list itself: this page is drawn only from the 30.19 section of the official whatsnew.txt shipped inside the verified 30.19 build 20 packages. Items are paraphrased faithfully rather than decorated, and anything not in that section is not presented here as a 30.19 change. That discipline matters because version summaries on the wider web often mix changes from several releases into one list. One related detail worth knowing: the source package for this release is labelled build 21, while the distributed binaries are build 20. That difference is in the official distribution itself and is not a sign of a wrong download. Platform and version guidance across the site is indexed on the platforms hub.
The seven changes in 30.19
| # | Change, as recorded in whatsnew.txt | Who it affects |
|---|---|---|
| 1 | Edwards ECM curves are now used in place of the previous Montgomery ECM curves, and are about 10 percent faster when sufficient memory is available. | GIMPS contributors running ECM factoring work |
| 2 | ECM stage 2 can now be run using a GMP-ECM resume file, for example alongside a GPU running stage 1, using the new worktodo entries ECMSTAGE2 and ECMSTAGE2N. | Contributors splitting ECM work between GPU and CPU tools |
| 3 | A timestamp option has been documented in undoc.txt, the file that records the program’s less common settings. | Advanced users who work with the documented settings file |
| 4 | The Manual Communication menu item now also initiates a proof upload, rather than only handling the communication step. | Contributors who use manual communication, including offline machines |
| 5 | In the Test / PrimeNet dialog, enabling Use Primenet now first brings up the Test / Worker Windows dialog, so work preferences can be adjusted at the moment they become relevant. | Anyone enabling PrimeNet work through the dialog |
| 6 | Runtime estimates comparing P-1 and ECM stage 2 against stage 1 have been calibrated against actual observed runtimes, improving the B2 calculation that depends on them. | Contributors running P-1 and ECM work, through better planning values |
| 7 | The Advanced / Test menu can now generate a PRP worktodo entry for a large exponent. | Advanced users setting up PRP work manually |
Read as a group, the pattern is clear. Four of the seven items improve the machinery of GIMPS contribution work: faster ECM curves, a more flexible ECM stage 2 that can continue from a GMP-ECM resume file, better runtime estimates for factoring stages, and easier manual setup of PRP work. Two items smooth communication and setup behaviour, proof uploads through Manual Communication and the worker preferences appearing when PrimeNet is enabled. One item, the timestamp option in undoc.txt, is a small power-user addition. None of the seven touches the Torture Test, the FFT presets, the AVX code paths or the stress.txt guidance, and this page will not pretend otherwise to make the release sound larger than it is.
How 30.19 relates to 30.18
The release immediately before this one, 30.18, recorded a single change in whatsnew.txt: a faster generic mod operation, noted as mainly benefiting external programs of the PFGW type that build on similar arithmetic. In other words, 30.18 was a one-line release and 30.19 is a seven-item release, and both are typical of this project’s mature phase, in which changes arrive as precise, technical adjustments to the prime-searching machinery rather than as interface redesigns. For a stress tester, the practical difference between the two builds is negligible; for a contributor, 30.19 is the more meaningful step, particularly for ECM work. The longer record, release by release and drawn from the same official file, is maintained on the version history page.
How to upgrade to 30.19 build 20
Upgrading follows the program’s portable design. First, download the verified package for your system from the download page and check its SHA-256 against the listed value, so the new build starts from a file you can account for. Second, protect your existing setup before changing anything: copy your current Prime95 folder, or at least its prime.txt settings file and your results files, to a safe place, because those files carry your worker configuration, any prime.txt options you have set, and the record of tests already run. Third, extract the new package, either into a fresh folder, moving your saved prime.txt and results files across, or over the existing folder if you prefer to keep one working directory; either way, confirm afterwards that your settings file survived with your options intact and that the program reports the new version when it starts. Fourth, run a short Torture Test before any long session, not because the release demands it, but because verifying a changed setup with a brief checked run is the same good habit this site recommends after any settings change. If anything looks wrong, your untouched backup folder restores the previous build exactly as it was.
Should stress testers bother upgrading?
Yes, as a matter of routine, with expectations set correctly. You gain a program whose change list you can read in full on one page, whose GIMPS machinery is current, and whose behaviour matches the documentation and guides written for 30.19, including every guide on this site. You should not expect a different stress testing experience: Small FFTs remains the maximum power and heat preset, Blend remains the default, preset sizes are still chosen from cache size as they have been since version 29.8, and the stress.txt recommendation of 6 to 24 hours for a thorough check is unchanged. Upgrading keeps your tools and your references in step with each other, which is reason enough, and it costs one verified download and a few minutes of care with two small files.
Bottom line
Version 30.19 build 20 is seven honest, technical changes, mostly in service of the prime search that is the program’s real job. Take the upgrade from the download page, keep prime.txt and your results safe while you do it, and expect your next Torture Test to feel exactly like the last one, which is precisely what a maintenance release should feel like. The full release record lives on the version history page.