CPU-Z is a free utility that collects and displays information about system hardware, including including CPU, Motherboard, and RAM. It can also display some software information, including Windows and DirectX versions. Available for Windows XP / Vista / Windows 7, you can use CPU-Z to monitor clock/core speeds, bus speeds, voltages, timings etc.
Unlike other sources of information (IE, Windows computer properties, speccy, etc.), CPU-Z updates the information in real time, allowing you to see if your processor is correctly underclocking to save power or correctly overclocking for Turboboost. Because of this, it's quite easy to determine CPU-Z as an essential tool for troubleshooting or tinkering.
According to the website, CPU-Z displays the following information about your system: