Recs.
Updated
Super PI is a benchmarking software that tests your CPU specifically by calculating the infinite number pi to a decimal point of up to 32 million digits.
Specs
Pros
Pro Calculates different increments of pi
You can adjust the settings of Super PI to only calculate Pi up to a certain amount of decimals. For example, you can use a test for 512.000 digits for a quick reference, while a calculation of 32 million digits will be longer and more thorough.
Cons
Con Only tests a single CPU-thread
Super PI is a single threaded program, which means it's only capable of benchmarking a single thread of your CPU. Current CPU's generally have four threads or more. The testing method of Super PI isn't optimized for modern CPU's and this measure is quickly becoming less and less important.
Con Credibility concerns for online results
Super PI has quite a competitive nature, with people attempting to reach the quickest scores in order to get a record. There have been fraudulent results in the past and with a bit of tinkering, it's possible to produce inaccurate time results.