OCCT (OverClock Checking Tool) is very appreciated among the so-called oveclockers a tool to test the underlying computer components that have been "overclocked" to achieve the highest possible performance. It also provides detailed information, including about your processor.
3DMark Basic Edition is a free version of one of the most famous benchmarks, offering the user a number of 3D graphics and CPU stress tests, with which you can evaluate the performance and stability of a computer
GPU-Z is an excellent utility for viewing various information about the video card and its graphics processor, such as model, BIOS version, chip revision number, DirectX support, and much more. Works with NVIDIA and ATI cards
Sysinternals Suite - a large set of useful tools for diagnosing and troubleshooting various kinds of system problems from Mark Russinovich, a well-known technical specialist, co-founder of Winternals Software, and now an employee of the company