Best free PC Benchmark tools for Windows

Prime95 - test system stability. Prime95 has become extremely popular among PC enthusiasts and overclockers as a stability testing utility. It includes a "Torture Test" mode designed specifically for testing PC subsystems for errors in order to help ensure the correct operation of Prime95 on that system, which effectively stress-tests a PC.

HD Tach - hard drive benchmark tool that tests the sequential read, random access and interface burst speeds of the attached storage device (hard drive, flash drive, removable drive etc). Drive technologies such as SCSI, IDE/ATA, IEEE 1394, USB, SATA and RAID are supported.

CrystalMark - benchmark suite, that lets you to test your CPU, memory, HDD and video (GDI, Direct Draw, OpenGL).

NoveBench

• Extensive CPU speed tests
• Multi-threaded tests take advantage of multiple cores/processors
• Hardware accelerated graphics tests
• Hard drive write speed test
• CPU temperature monitor
• Tabbed interface for benchmark results
• Outputs overall system score
• Online score comparison system.
• Freeware.