You can download a utility program from Intel that will not only ID the CPU, but run tests to determine if the CPU is running at the intended frequency. This utility is located at the following site:
First, the speed is printed on the surface of the chip or module; look for a processor code – something similar to “B80523P333512E SL2WY”. This indicates a speed of 333MHz.
You can also use the code above to search the Intel site for more detailed information.
You can also get a processor description from the System Properties dialog box; right-click on the “My Computer” icon, then click on Properties. Under the heading “Computer:” will be a string similar to “Family 6 Model 8 Stepping 3”. Searching the intel site using this string reveals a Pentium III processor running at approx. 600 MHz.