CPU-Z is a freeware that gathers information on some of the main devices of your system.

CPU
* Name and number.
* Core stepping and process.
* Package.
* Core voltage.
* Internal and external clocks, clock multiplier.
* Supported instruction sets.
* Cache information.

Mainboard
* Vendor, model and revision.
* BIOS model and date.
* Chipset (northbridge and southbridge) and sensor.
* Graphic interface.

Memory
* Frequency and timings.
* Module(s) specification using SPD (Serial Presence Detect) : vendor, serial number, timings table.

System
* Windows and DirectX version.