Alexander J. Yee & Shigeru Kondo claim to have computed pi to 5 trillion digits using nothing but a desktop computer - a fairly up market machine with 12 physical cores and 24 hyperthreads, 96GBytes of Ram and 40TByes of disk storage.
The machine that did the computation
(Alexander J. Yee & Shigeru Kondo)
To be clear Pi to 5 Trillion digits is 5,000,000,000,000 digits and the computation took 90 days to complete and 66 hours to verify. This is 2.3 trillion digits more than the previous record.and the file needed to store the results is 3.8 TBytes even using compression.
The key to the success is y-cruncher, a multi-threaded computation program. This program also holds the records for computing other constants to extreme precision - e, square root of 2 and so on.
The only question that remains is - why?
Yee's answer is: "Because it's Pi ... and because we can!"
Of course there is a lot hidden in that phrase "Because it's Pi" which the average human will simply miss.
On a more practical note using the parallelism offered by multiple cores to perform computations that once needed a supercomputer is interesting - it's a proof of principle. The same principles could be turned to other problems such as code generation and code cracking.