How Processor Speed Is Reported to a Computer

This article describes how the processor speed is reported in Windows XP.

The System tool in Control Panel uses currentspeed to do its reporting rather than maxspeed, but the System tool may display the wrong clock speed for the Central Processing Unit (CPU).

As of January 2002, Windows XP uses the currentspeed value rather than the maxspeed value because the maxspeed value was reporting inconsistent values.

After startup, the processor may not correctly reflect its correct speed until a program utilizes processor cycles.

The computer basic input/output system (BIOS) in some laptop computers may throttle the processor because of heat, load, power AC/DC.

To check the currentspeed setting:

1. Click Start, click Control Panel, and then click Performance and Maintenance.
2. Click See basic information about your computer. On the General tab, the processor speed (in MHz) appears under Computer.

To check the maxspeed setting:

1. Click Start, point to All Programs, point to Accessories, point to System Tools, and then click System Information.
2. The speed (Maxspeed) of the processor appears in MHz in the System Information window, in the right column of System Summary, under Processor..

NOTE: System Information from Administrative Tools always reports Maxspeed.

If you click Start, point to All Programs, point to Accessories, point to System Tools, and then click System Information, the correct processor speed (for example, 797 MHz = 800 MHz) is shown. After you start the System Information tool, the System Properties tool in Control Panel displays the correct speed. However, when you first start your computer, the incorrect speed is shown in the System Properties tool in Control Panel.