Super PI is a computer program that calculates pi to a specified number of digits after the decimal point—up to a maximum of 32 million. It uses Gauss–Legendre algorithm and is a Windows port of the program used by Yasumasa Kanada in 1995 to compute pi to 232 digits.
Super PI is used by many overclockers to test the performance and stability of their computers. In the overclocking community, the standard program provides a benchmark for enthusiasts to compare "world record" pi calculation times and demonstrate their overclocking abilities. The program can also be used to test the stability of a certain overclock speed. If a computer is able to calculate pi to the 32 millionth place after the decimal without mistake, it is considered to be moderately stable in terms of RAM and CPU. However, longer tests with other CPU/RAM intensive calculation programs will run for hours instead of minutes and may give and/or provide better stress system stability. Super PI is not the fastest program for calculating pi (see software for calculating π for faster alternatives), and it is losing favor in overclocking and benchmarking circles because of its arguably poor representation of real world benchmarks: it uses x87 floating point instructions which are typically used for high precision scalar numerical calculations, whereas multimedia and vector calculations often use SIMD instructions.
The competitive nature of achieving the best Super PI calculation times led to fraudulent Super PI results, reporting calculation times faster than normal. Attempts to counter the fraudulent results resulted in a modified version of Super PI, with a checksum to validate the results. However, other methods exist of producing inaccurate or fake time results, raising questions about the program's future as an overclocking benchmark.
Super PI utilizes x87 floating point instructions which are supported on all x86 and x86-64 processors, current versions which also support the lower precision Streaming SIMD Extensions vector instructions.
Super PI is single threaded, so its relevance as a measure of performance in the current era of multi-core processors is diminishing quickly. Therefore, Hyper PI has been developed to support multiple threads of Super PI to be run at the same time so one can test stability on multi-core machines. Other multithreaded programs include: wPrime, IntelBurnTest, Prime95, Montecarlo superPI, OCCT or y-cruncher. Last but not least, while SuperPi is unable to calculate more than 32 millions, Alexander J. Yee & Shigeru Kondo were able to set a record of 10 Trillion 50 Digits of Pi using y-cruncher under a 2 x Intel Xeon X5680 @ 3.33 GHz - (12 physical cores, 24 hyperthreaded) computer on October 16, 2011
- Round 2... 10 Trillion Digits of Pi, numberworld.org