CPU-Z is primarily used to fully detect the CPU and Motherboard hardware of PCs. Without programs like this, a PC user would be less able to fully use the hardware available to them.
CPU-Z is more in-depth in virtually all areas compared to the tools provided in the Windows OS to identify various hardware components, and thus assists in identifying certain components without the need of opening the case; particularly the core revision and RAM clock rate. Most recently, a graphics card tab has been added.
CPU-Z has an ability to directly detect hardware features, such as the ability to access, read, and display the SPD data from memory modules. The ability to document clock speed makes it a tool for motherboard overclockers, as a way of proving the CPU speeds achieved by various experiments.