Technically, it’s the end user client for a distributed compting project to find new Mersenne prime numbers, but Prime95 is also a great tool for PC system builders. In its tortue test mode Prime95 will put a 100% processing load on the CPU... that'll prove if the cooling system you installed on your CPU is doing a good job. DIY PC builders and overclockers have been using it for years to gauge their systems reliability. You should, too!