Prime95 is also known as Great Internet Mersenne Prime Search (GIMPS). It is a tool to find World Record Primes. However, it can be used as CPU torture tool as well. It is a great tool to stress your CPU because the torture test will use up all your CPU core and 100% CPU utilization. Who want to torture his own CPU anyway? Overclocker like me will need it. Besides this tool, I also use SpeedFan to monitor CPU temperature and CPU-Z for CPU core speed and bus speed.