SpeedFan is a freeware program that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. info for those hard disks that support this feature and show hard disk temperatures too, if supported. SpeedFan supports SCSI disks too. SpeedFan can even change the FSB on some hardware (but this should be considered a bonus feature).

SiSoftware Sandra (the System ANalyser, Diagnostic and Reporting Assistant) is an information & diagnostic utility. It should provide most of the information (including undocumented) you need to know about your hardware, software and other devices whether hardware or software.

Fraps is a universal Windows application that can be used with all games using DirectX or OpenGL technology. In its current form Fraps performs many tasks and can best be described as:

EVEREST Home Edition is a freeware hardware diagnostics and memory benchmarking solution for home PC users, based on the award-winning EVEREST Technology. It offers the world's most accurate hardware information and diagnostics capabilities, including online features, memory benchmarks, hardware monitoring, and low-level hardware information

CPU-Z is a freeware utility that gathers information on some of the main devices of your system. CPU-Z does not need to be installed, just unzip the files in a directory and run the .exe. In order to remove the program, just delete the files and that's it. The program does not copy any file in any Windows directory, nor write in the registry.

3DMark03 is a great benchmarking program for your gaming PC. By combining full DirectX 9.0a support with completely new tests and graphics, 3DMark03 continues the legacy of being the industry standard benchmark.