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  Topic Review (Newest First)
12-21-2017 02:39 AM
stasio Prime95v.29.4 Build 5


1) GIMPS has a new sub-project -- finding (probable) prime Mersenne cofactors.
This sub-project has two parts: 1) Running PRP tests, and 2) Finding
additional factors. To support this new sub-project there are three
new work preferences: PRP on Mersenne cofactors, PRP double-checking on
Mersenne cofactors, ECM on Mersenne cofactors.
2) Like LL tests, PRP tests now support shift counts to aid in running double-checks.
Shift counts are only supported for Mersenne numbers and Mersenne cofactors.
3) PRP tests now support a type of low overhead error checking that almost guarantees
correct results even on flaky hardware. We call this Gerbicz error-checking after
it was proposed by Robert Gerbicz at mersenneforum.org. This error-check only
works for base-2 numbers.
4) Because PRP tests are highly reliable, we now offer the option to do PRP tests
instead of Lucas-Lehmer primality tests. There are 3 new work preferences
similar to LL work preferences: first-time PRP tests, world record PRP tests,
PRP tests on 100 million digit numbers, and PRP double-checking.
If you are looking for a 100 million digit prime, PRP testing is recommended
rather than LL testing.
5) For non-base-2 PRP tests, there is a new option to run each iteration twice and
rollback if a mismatch occurs. Useful only on flaky hardware due to the obvious
high overhead.
10-16-2017 07:28 PM
Skylinestar Prime95 v29.3
Released: 2017 Sep 07
10-31-2016 02:36 PM
stasio Prime95v.28.10 Build 1

08-10-2016 09:03 PM
OCmember Are there any issues with the latest 28.9 build 2 and older platforms like X58 ?
03-29-2016 06:38 PM
stasio Prime95v.28.9 Build 2


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.
08-13-2015 11:05 PM
stasio Prime95v.28.7 Build 1


04-16-2015 09:18 PM
kevindd992002 Does this new version have any effect if I'm using it for stress testing only and my CPU is SB?
04-16-2015 01:03 AM
stasio Prime95v.28.6 Build 1


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!!!
01-28-2015 07:32 PM
kevindd992002 BUMP!
01-26-2015 06:06 PM
kevindd992002 BUMP!
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