# New Prime95- version 26.3, build 3



## 95Viper (Oct 15, 2010)

A new version of Prime95 has been released.
Version 26.3, build 3

x86 version: p95v263.zip

64 bit version: p64v263.zip

New features in Version 26.3 of prime95.exe
-------------------------------------------

1)  A few crash bugs were fixed that affected only some CPU architectures and some
    FFT lengths.  Other minor bugs were fixed.

Enjoy 

EDIT: Thank You, stasio, for keeping this thread updated.


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## stasio (Nov 16, 2010)

*Prime95 v26.4 *

ftp://mersenne.org/gimps/p95v264.zip
ftp://mersenne.org/gimps/p64v264.zip

1) The length 160K x87 FFT crashes. Fixed in 26.3 build 2.
2) The length 4M FFT crashes on Northwood and Willamette Pentium 4. Fixed in 26.3 build 3.
3) On a brand new install, the default on hyperthreaded machines was 2 threads per worker. This was slower for most users. In the next release, the default will be 1 thread per worker.
4) Testing 522*928^24576-1 in 64-bit executables crashes. Fixed in 26.4.
5) You cannot edit the affinity settings from the Linux menus. Fixed in 26.4.
6) Running a multi-threaded torture test on AMD machines failed. Fixed in 26.4.
7) Setting a specific FFT length in worktodo.ini sometimes selects the next larger FFT length. This would most commonly occur when an exponent being tested is near the FFT crossover point and a specific FFT length is automatically chosen based on the roundoff error in the first 1000 iterations. Fixed in 26.4.
8) Multi-line additional information from the Primenet server was not parse properly. Only the first line was parsed. Thus, when successfully completing a double-check only the successful completion was written to prime.log. The cpu credit amount was not written to prime.log. Fixed in 26.4.
9) When doing PRP on non-base-2 numbers the time estimate in Test/Status was off by a factor of log2(base). Fixed in 26.4.
10) On a 32-bit Mac, some FFT implementations were missing. Fixed in next release.


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## 3volvedcombat (Nov 16, 2010)

Its working. My q9550 is producing such a little amount of heat. That my temps barly drop like 5-8c after i stop prime 95.

and All my cores stay at or under 40c at full load, for hours.

yay prime 95!!!!!


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## UseNow (Nov 16, 2010)

When was v26.4 released?


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## 95Viper (Nov 16, 2010)

Looks like 11/13/2010


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## mastrdrver (Jan 30, 2011)

Thank you stasio. I found 26.4 x64 once but lost it and all I could find was the x86 version.


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## stasio (Feb 9, 2011)

*Prime95 v26.5*

ftp://mersenne.org/gimps/p95v265.zip
ftp://mersenne.org/gimps/p64v265.zip

1) Pentium 4s and Celerons with L2 cache size of 256K or less choose a length 4M FFT when they could use an FFT between 1600K and 4M in size. Fixed in next release.
2) The on screen message reporting that errors have occurred during the LL test was wrong. The counts for "SUM(INPUTS) != SUM(OUTPUTS)" and "ROUNDOFF > 0.4" were reversed. Fixed in next release.
3) Dual-boot users running a 32-bit and 64-bit executable on the same exponent may experience "Unable to initialize FFT" message. This happens when prime95 writes an FFT size to worktodo.txt and that FFT size is only supported by just one of the two executables. For example, the 2240K FFT length is supported for 64-bit Core 2 but not 32-bit Core 2. Fixed, somewhat inelegantly, in 26.5 -- unimplemented FFT lengths are ignored when worktodo.txt is read.
4) Prime95 will sometimes inexplicably unreserve exponents. I think this happens when prime95 incorrectly calculates the CPU speed. Version 26.5 will only use a new slower CPU speed measurement after several slower CPU measurements. Hopefully, this will resolve the unreserve problem caused by a single erroneous CPU speed measurement.
5) Prime95 would lose the how_far_factored and tests_saved information on PRP= lines in worktodo.txt. Fixed in 26.5.
5) Prime95 did not offer an option to delete P-1 save files when a work unit completes. Fixed in 26.5.
6) Prime95 did not fully understand Sandy Bridge CPUID output. Fixed in 26.5.
7) Prime95 did not accurately report the CPU speed. Fixed in 26.5.
8) At startup, the workers threads do not start up properly until communication with the server completes. If you have a large worktodo.txt file, this will result in wasted CPU time and many "use count" error messages. Fixed in 26.5.
9) Time estimates for trial factoring to 2^79 and above were incorrect. Fixed in 26.5.


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## stasio (Feb 11, 2011)

*Prime95 v26.5 Build 2*

ftp://mersenne.org/gimps/p95v265.zip
ftp://mersenne.org/gimps/p64v265.zip

1)  Minor bug fixes.
2)  Starting in build 2, P-1 work will display the chance of finding a factor.
    The worktodo.txt line must include how_far_factored using the new syntax:
	Pminus1=k,b,n,c,B1,B2[,how_far_factored][,B2_start][,"factors"]


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## stasio (Feb 19, 2011)

*Prime95 v26.5 Build 3*

ftp://mersenne.org/gimps/p95v265.zip
ftp://mersenne.org/gimps/p64v265.zip

Starting with build 3, at startup the program tries to determine which
hyperthreaded logical CPUs comprise one physical CPU. If this isn't working
properly, see the AffinityScramble2 setting in undoc.txt. The previous
version's AffinityScramble setting is no longer supported!


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## stasio (Feb 22, 2011)

*Prime95 v26.5 Build 4*

ftp://mersenne.org/gimps/p95v265.zip
ftp://mersenne.org/gimps/p64v265.zip


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## stasio (Feb 22, 2011)

*Prime95 v26.5 Build 5*

ftp://mersenne.org/gimps/p95v265.zip
ftp://mersenne.org/gimps/p64v265.zip

-Fixes the dual-core non-SSE2 benchmark crash


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## stasio (Mar 4, 2011)

*Prime95 v26.6 Build 1*-x64 only

ftp://mersenne.org/gimps/p64v266.zip

-For rare cases where the program cannot figure out the number of cores and hyperthreading,
the NumPhysicalCores option may help.


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## stasio (Apr 3, 2011)

*Prime95 v26.6 Build 2*-x86 only

ftp://mersenne.org/gimps/p95v266.zip


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## stasio (Apr 9, 2011)

*Prime95 v26.6 Build 3*

ftp://mersenne.org/gimps/p95v266.zip
ftp://mersenne.org/gimps/p64v266.zip

http://www.mediafire.com/?1m7y1kfv9vbj618

1) Occasionally, P-1 stage 2 would report 100% complete before stage 2 completed. This bug has been around forever. I've finally found the cause! Fixed in 26.5 build 2.
2) Worktodo.txt was not updated properly when P-1 completed for a PRP test. Fixed in 26.5 build 3.
3) In 26.5 build 3, when benchmarking and measuring CPU speed the program will keep all cores busy by launching auxiliary threads that loop indefinitely. This should prevent Intel Turbo boost from kicking in. This should prevent cases where the CPU speed is reported as 1.87 GHz, yet a benchmark reports very fast timings because the CPU core has been boosted to 3.2 GHz because only one core is active.
4) In 26.5 build 3, the OS's mapping of hyperthreaded logical CPU numbers to physical CPUs is determined automatically at startup. The AffinityScramble setting (see undoc.txt) is no longer supported. It is replaced by the AffinityScramble2 setting.
5) In 26.5 build 3, the message "set affinity to run on any cpu" instead listed all the CPU numbers and as well as CPU #31. Fixed in build 4.
6) In 26.5 build 3 and 4, benchmarking a dual-core non-SSE2 machine will crash. Fixed in build 5.
7) KeepPminus1SaveFiles=0 option described in undoc.txt did not work when a factor was found. Fixed in 26.6.
8) The 32K,64K,80K length FFTs with sumout checking for Pentium 4's with 256K or less cache were not implemented. Symptom is a torture test failure. Fixed in 26.6.
9) Prime95 does not load on Sandy Bridge CPUs running Win XP. I've got a trial fix in 26.6.
10) Prime95 chooses very inefficient FFT implementations for Core 2 Celerons (they have 512K L2 cache). Working on a fix for for 26.6.
11) Logical CPU numbers were sometimes output zero-based and sometimes one-based. In 26.6, they are all one-based.


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## stasio (Dec 7, 2011)

*Prime95 v27.1 Build 1
*
ftp://mersenne.org/gimps/p95v271.zip

From developer:


> A very early pre-beta prime95 version 27.1 is available. It has support for most, but not all AVX FFT lengths. I have not done any of the 64-bit optimizations.
> 
> I've been using this version on my Sandy Bridge for the last few days without incident. You are free to do so too. I'm fairly confident it will produce valid results as it has passed some torture testing and QA runs. If you do not have a Sandy Bridge CPU (or maybe a Bulldozer) there is absolutely no reason to download this version. In fact it would be dangerous to do so as I have not tested the SSE2 or x87 FFTs to see if I've broken something!


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## stasio (Feb 17, 2012)

*Prime95 v27.3 Build 1*

ftp://mersenne.org/gimps/p95v273.zip
ftp://mersenne.org/gimps/p64v273.zip

This version supports 64-bit optimized AVX FFTs. 32-bit AVX FFTs are also a little bit faster. I haven't done full benchmarks so I'm not sure how much faster it is than versions 27.2 or 26.6.

The good/bad news is these FFTs are so fast that they are limited by memory bandwidth -- standard Sandy Bridge CPUs will experience a slow down when running all 4 cores. I'd like to hear from Sandy Bridge-E users to see if they also suffer slow downs when all 4 cores are running.


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## stasio (Mar 9, 2012)

*Prime95 v27.4 Build 1*

ftp://mersenne.org/gimps/p95v274.zip
ftp://mersenne.org/gimps/p64v274.zip

This version fixes a number of bugs in 27.3 - mostly related to LLR and PFGW issues. There are no speed improvements over 27.3. Hopefully, Bulldozer processors now properly run SSE2 FFTs.


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## stasio (Apr 25, 2012)

*Prime95 v27.6 Build 1*

ftp://mersenne.org/gimps/p95v276.zip
ftp://mersenne.org/gimps/p64v276.zip

1)  Multi-threaded tests might be a little bit faster especially when using a lot of threads.
    Of course, single-threaded usage still gives the best throughput.
2)  FFT crossover points were adjusted.  Many higher, a few lower.


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## Drone (Apr 25, 2012)

download stops at 99% how lame


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## stasio (Apr 27, 2012)

*Prime95 v27.6 Build 2*

ftp://mersenne.org/gimps/p95v276.zip
ftp://mersenne.org/gimps/p64v276.zip

1. A slower trial factoring algorithm is chosen sometimes. Fixed in version 27.6 build 2.


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## Drone (Apr 27, 2012)

As always won't download. Any alternative links?


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## stasio (Apr 28, 2012)

Drone said:


> As always won't download. Any alternative links?



http://www.benchmarkhq.ru/english.html
http://www.mersenneforum.org/gimps/

*Prime95 v27.6 Build 3*

ftp://mersenne.org/gimps/p95v276.zip
ftp://mersenne.org/gimps/p64v276.zip

The round off error can be incorrectly calculated. Fixed in 27.6 build 3.


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## stasio (May 2, 2012)

*Prime95v.27.6 Build 4 (32/64-bit)*

ftp://mersenne.org/gimps/p95v276.zip
ftp://mersenne.org/gimps/p64v276.zip

- Mprime -v does not print out the build number. Fixed in version 27.6 build 4.
- Torture test on small FFTs gets round off errors or crashes after a while. Fixed in version 27.6 build 4


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## stasio (May 4, 2012)

*Prime95v.27.7 Build 1 (32/64-bit)*

ftp://mersenne.org/gimps/p95v277.zip
ftp://mersenne.org/gimps/p64v277.zip

Torture test on small FFTs gets round off errors or crashes after a while. In very rare cases, regular tests could crash or raise a round off error. Fixed in version 27.7.
Multithreaded FFTs could deadlock. Fixed in version 27.7.


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## stasio (May 16, 2012)

*Prime95 v27.7 Build 2
*

Windows 64-bit: ftp://mersenne.org/gimps/p95v277.win64.zip
Windows 32-bit: ftp://mersenne.org/gimps/p95v277.win32.zip

1. SoB cannot package a default prime.txt with the Mac OS X version because the Mac version changes the working directory to ~/Prime95. Mac version changed to copy a prime.txt file from the application bundle to ~/Prime95. Fixed in version 27.7 build 2.
2. Root cause of several false prime reports in recent years found. Fixed in version 27.7 build 2.


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## stasio (Dec 13, 2012)

*Prime95 27.9 Build 1 *

ftp://mersenne.org/gimps/p95v279.win32.zip
ftp://mersenne.org/gimps/p95v279.win64.zip

- minor bug fixes


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## stasio (Aug 30, 2013)

*Prime95v.28.1 Build 1 (64-bit)*

http://www.mediafire.com/?awambpo41sy6qns

From developer:


> For any Haswell owners that are interested, an evaluation version 28.1 is available. I have some ideas to improve it further, but they will take some time to implement.
> 
> I sure hope it works correctly because I've started using it on my Haswell box


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## stasio (Sep 12, 2013)

*Prime95v.28.1 Build 2 (64-bit) *

http://www.mediafire.com/?pj2erd72t1oyb8n

- fixed the bad self-test data


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## d1nky (Sep 12, 2013)

thanks, does this also detect correctly vishera cpus?


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## tom_mili (Sep 12, 2013)

Tried with my Haswell and it is harder to pass than prime95 with AVX. My previous stable setting on Prime95 AVX wont stable with this which means more time for tinkering


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## stasio (Jan 13, 2014)

*Prime95v.28.3 Build 1 Beta (32/64-bit)*

ftp://mersenne.org/gimps/p95v283.win32.zip
ftp://mersenne.org/gimps/p95v283.win64.zip
ftp://mersenne.org/gimps/p95v283.linux64.tar.gz
ftp://mersenne.org/gimps/p95v283.MacOSX.zip



> Prime95 version 28.3 is available. This version is for you intrepid beta testers. I've run the torture test and done some QA, but I haven't run any double-checks yet. I don't expect any problems, and I am now using it on my computers.
> 
> This version includes nearly all the Haswell optimizations I plan on implementing. A few of these changes may also benefit Sandy/Ivy Bridge machines. On my Sandy Bridge I'm seeing a 1.5% improvement.


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## Jetster (Jan 13, 2014)

Should be called Prime14


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## Octopuss (Jan 13, 2014)

Why?

Stasio, are you registered on ALL IT related forums around the world? I honestly can't think where I didn't see you yet, lol.


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## Jetster (Jan 13, 2014)

Or Prime 8. Because we are past "95"


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## stasio (Feb 24, 2014)

*Prime95v.28.4 Build 1 Beta*

ftp://mersenne.org/gimps/p95v284.win32.zip
ftp://mersenne.org/gimps/p95v284.win64.zip
ftp://mersenne.org/gimps/p95v284.linux64.tar.gz
ftp://mersenne.org/gimps/p95v284.MacOSX.zip

Reduced memory usage.  
This may make some single-thread benchmarks slower, but when
 running several workers on machines where memory is a bottleneck there should be a
 small performance increase.


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## stasio (Mar 7, 2014)

*Prime95v.28.5 Build 1 Beta*

ftp://mersenne.org/gimps/p95v285.win32.zip
ftp://mersenne.org/gimps/p95v285.win64.zip
ftp://mersenne.org/gimps/p95v285.linux64.tar.gz
ftp://mersenne.org/gimps/p95v285.MacOSX.zip

1) Changed the output to the worker windows during LL and PRP tests. The new output includes
the estimated time to complete the test. There are two new options described in undoc.txt:
ClassicOutput and OutputRoundoff.
2) Added some new options described in undoc.txt: ScaleOutputFrequency, TitleOutputFrequency,
and SilentVictoryPRP.
3) Benchmarking on hyperthreaded machines now times only the most common cases. Specifically,
hyperthreading is used only in the one cpu and all cpu cases.
4) Benchmarking trial factoring is now off by default. Prime95 should not be used for trial
factoring. GPUs are about 100 times more efficient at that task.
5) On multi-core machines, benchmarks are now run on multiple workers. This measures the effect
of memory bandwidth during testing and helps you select the setup that gives you the most throughput.
6) There are many new options described in undoc.txt to customize the benchmarking process


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## stasio (May 30, 2014)

*Prime95v.28.5 Build 2 *

http://mersenneforum.org/gimps/p95v285.win64.zip
http://mersenneforum.org/gimps/p95v285.win32.zip
http://mersenneforum.org/gimps/p95v285.MacOSX.zip



-added a preference to bypass some of Mac OS X Mavericks' power saving features.


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## Aquinus (May 30, 2014)

@stasio : Your last few posts with links to ftp are broken. The link itself (not the text,) is missing a colon after ftp so links are coming up ftp//mersenne.org/gimps/p95v285.zip. Try clicking on the links and you'll see what I mean.


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## stasio (May 31, 2014)

All links here:

ftp://mersenne.org/gimps/
or
http://mersenneforum.org/gimps/


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## stasio (Apr 16, 2015)

Prime95v.28.6 Build 1

ftp://mersenne.org/gimps/p95v286.win32.zip
ftp://mersenne.org/gimps/p95v286.win64.zip

1)  The "days between sending new end dates" preference now accepts values between 0.125 and
  7.0 (was between 1 and 7).  This lets you contact the server as frequently as every three
  hours.  This can be useful in conjunction with the server feature that sends an email to
  you if the computer is more than one hour late contacting the server.  To turn on that
  server feature, go to the CPUs web page, and click on the CPU, there you can turn on a
  couple of email features.
2)  AVX2 support for trial factoring.  About a 50% speedup over the previous version.  However,
  all trial factoring should still be done on a GPU.  A GPU is on the order of 100 times more
  efficient at trial factoring than a CPU!!!


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## stasio (Aug 14, 2015)

*Prime95v.28.7 Build 1*

ftp://mersenne.org/gimps/p95v287.win32.zip
ftp://mersenne.org/gimps/p95v287.win64.zip

http://mersenneforum.org/showthread.php?s=75522f8c24a2fb9204ad692e2ca080ba&t=20156


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## stasio (Mar 30, 2016)

*Prime95v.28.9 Build 2*

ftp://mersenne.org/gimps/p95v289.win32.zip
ftp://mersenne.org/gimps/p95v289.win64.zip

New features in Version 28.9 of prime95.exe
-------------------------------------------

1) Since GPUs are so much better at trial factoring than CPUs, benchmarking no longer times
prime95's trial factoring by default. Two new benchmarking options are available:
OnlyBenchThroughput and OnlyBenchMaxCPUs. See undoc.txt for details.
2) Slightly reduced the memory bandwidth requirements for several large FFTs. May lead to
a very small speed increase for users testing 100 million digit numbers.
3) If running more than worker, prime95 looks for any sin/cos data that it can share among
the workers. Depending on the FFT sizes you are running, this could lead to a very slight
reduction in needed memory bandwidth.
4) Method for choosing the best FFT implementation changed. In previous versions, the FFT
implementation that resulted in the fastest single worker timing was used. In this version
the FFT implementation that had the best throughput was selected. For FMA3 FFTs I used a
4-core Skylake to measure best throughput. For AVX FFTs I used a 4-core Sandy Bridge
to measure best throughput. Not many FFTs were affected, but you may see a few percent
variation in throughput with this version.
5) Improved AVX2 trial factoring in 64-bit executable. Trial factoring should still be done
on a GPU. A GPU is on the order of 100 times more efficient at trial factoring than a CPU!!!
6) Trial factoring now defines one "iteration" as processing 128KB of sieve, or 1M possible
factors. In previous versions an iteration was defined as 16KB of sieve in 32-bit executables
and 48KB in 64-bit executables. The trial factoring benchmark still times processing 16KB of sieve.
7) Trial factoring in 64-bit executables is now multi-threaded.
8) On initial install, the default settings for number of worker windows will be set to
the number of cores / 4 with multithreading turned on.
9) The worker windows dialog box now enforces a minimum number of multi-threaded cores for some
work types to ensure timely completion of assignments. Also, the worker windows menu choice
no longer allows assigning work to hyperthreads (they are rarely beneficial in prime95).
This behavior can be overridden with the ConfigureHyperthreads undoc.txt feature.


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## RejZoR (Mar 30, 2016)

Download links don't work


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## 95Viper (Mar 30, 2016)

You can ftp this directory and find them: ftp://mersenne.org/gimps/

For some reason the link button, in the editor, adds ""http://" in front of the ftp address.


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## Octopuss (Mar 30, 2016)

It would have been better if this stasio guy (who seems to be employed fulltime to post this sort of stuff on every single IT-related forum on the internet) posted a link to the appropriate forum instead of direct links that might change in future.


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## 95Viper (Mar 30, 2016)

Octopuss said:


> It would have been better if this stasio guy (who seems to be employed fulltime to post this sort of stuff on every single IT-related forum on the internet) posted a link to the appropriate forum instead of direct links that might change in future.



Your link in "appropriate forum" is not working... http://shihpoo/


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## Octopuss (Mar 30, 2016)

95Viper said:


> Your link in "appropriate forum" is not working... http://shihpoo/


What the hell? :-O What's going on @W1zzard? I posted a link leading here: http://www.mersenneforum.org/showthread.php?t=21159


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## stasio (Oct 31, 2016)

*Prime95v.28.10 Build 1
*
ftp://mersenne.org/gimps/p95v2810.win32.zip

ftp://mersenne.org/gimps/p95v2810.win64.zip


I took down the links to 28.9 because of recently discovered torture test issues on SSE2 machines.
There is little reason to upgrade from 28.7. Users have reported speeds plus-or-minus a couple of percent.


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## stasio (Mar 27, 2019)

*Prime95 v.29.7 Build 1*

ftp://mersenne.org/gimps/p95v297b1.win32.zip
ftp://mersenne.org/gimps/p95v297b1.win64.zip

1)  Support added for AVX-512 FFTs.
2)  FMA3 FFTs now have slightly higher FFT crossover points.  Soft crossovers are
    no longer used by default.  See undoc.txt.
3)  Torture test dialog box options now based on cache sizes.  Options for performing
    a weaker torture test are available.  Torture tests that use all RAM are now more
    stressful.  In-place vs. not in-place memory accesses now displayed on screen.
    On machines with more than 5GB of memory, blend defaults to all but 3GB of RAM.
4)  Add & subtract operations for AVX-512 FFTs are now multithreaded.  This should
    improve performance for P-1 and ECM when using multiple threads.
5)  Benchmark results are now written to results.bench.txt.
6)  JSON results are now available for all work performed.  JSON results are
    written to results.json.txt.
7)  PRP tests with Gerbicz error checking are more immune to hardware errors.


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## stasio (Aug 13, 2020)

*Prime95 v.30.3 Build 2*

ftp://mersenne.org/gimps/p95v303b2.win64.zip

Chanelog included in file.


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## stasio (Aug 31, 2020)

*Prime95 v.30.3 Build 4*

ftp://mersenne.org/gimps/p95v303b4.win64.zip

Chanelog included in file.


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## stasio (Sep 12, 2020)

*Prime95 v.30.3 Build 6*

ftp://mersenne.org/gimps/p95v303b6.win64.zip


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## stasio (Apr 21, 2021)

*Prime95 v.30.6 Build 1*

ftp://mersenne.org/gimps/p95v306b1.win64.zip


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