SpeedswitchXP - CPU frequency control for notebooks running Windows XP
NewsSpeedswitchXP version 1.52 is out (28. August 2006).
I've made the following changes to version 1.51:
SpeedswitchXP V1.52 (787 KB)
The previous version 1.4 can be downloaded from here.
SpeedswitchXP is a small applet that sits in the system tray and allows dynamic switching of the frequencies of mobile Intel and mobile AMD CPUs under Windows XP. During the development of Windows XP, Microsoft decided to integrate dynamic frequency switching into the operating system itself. On a default Windows XP installation, the power schemes in the power settings of the system panel control the frequencies of the processor. On Windows 2000 and previous operating systems, it was possible to manually control the CPU frequencies with a SpeedStep applet provided by Intel, but this is not possible anymore under Windows XP. It is not very good documented what the different Windows XP power schemes do and it is impossible to fully adjust the schemes as the important settings are not accessible through the control panel.
SpeedswitchXP tries to fill this gap in that it provides access to ALL power scheme settings. This small applet is similar in functionality to the native Intel SpeedStep applet for Windows 9x/ME and Windows 2000 but with a few more options.
Basically all it does is creating a power scheme under the power settings in the system panel and making this the default power scheme for Windows XP. When this is done, you can control all settings of this new scheme through the applet.
Since this program is using Windows XP's internal processor performance control functions, it should work on all notebooks that feature dynamic speed switching. So far, it has been successfully tested on notebooks with the following mobile CPUs:
Crash course for program usage
After starting the program, it automatically minimizes itself into the system tray. It can be identified by one of four different icons which indicate the current CPU policy:
If you move the mouse pointer over the tray icon, you see the current CPU policies for AC (external power) and DC (battery power) in a small popup window:
A rightclick on the tray icon opens a small window which allows fast switching between the different CPU policies:
When changing the CPU policy, the tray icon changes automatically to reflect the new CPU policy.
A leftclick on the tray icon opens the main window. It looks like this:
On the main window, you can change the CPU policies for both external and battery power. The program automatically switches between the external and battery CPU policies when a power state change occurs (pulling the AC plug or plugging it back in). You can also adjust the main power options here like display timeouts, HD spindown timeouts, etc.
Clicking on 'Detect max. speed' activates the detection of the CPU's maximum speed. This process takes approximately two seconds.
Clicking on the options button shows the options window:
These options have the following meaning:
The 'User policy', 'Machine policy' and 'CPU policy' tabs take you to the internal settings of the power scheme. Before you make any changes to these internal settings you should teach yourself on their internal functionality. I suggest that you read these documents to fully understand their meaning:
If you want to know even more about processor control and C-states then take a look at these sites:
Clicking on the 'Show system info' button on the main window brings up a window showing some info about the CPU and your system's power capabilities:
The second window tab shows your system's power capabilites:
© 2006 Christian Diefer
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Last Update: 28. August 2006