Prime95 28.10

January 30th, 2017 - What's New
  • 4.1 MB
    Win 10, 8, 7 (32-bit)
  • 5.4 MB
    Win 10, 8, 7 (64-bit)
Get Notified
Receive an E-Mail when this download is updated.
Publisher: GIMPS
Downloaded: 35,151 times (37.8 GB)
Popular system stability test program.

Version History

28.10 (January 30th, 2017)

  • 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.
  • 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.
  • If running more than one 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.
  • 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.
  • 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!!!
  • 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.
  • Trial factoring in 64-bit executables is now multi-threaded.
  • On initial install, the default settings for number of worker windows will be set to the number of cores / 4 with multithreading turned on.
  • 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.