Just a stab here, but maybe its the wrong drivers for the chipset.
Just a SWAG

 

The OS and/or BIOS settings could be throttling the CPU clock speed too. It may be an idea to check the power settings in Windows to see if there are any problems there. Does the laptop show the correct clock speed when you're connected to AC power supply?

 

Thanks for the answers.

I've installed the chipset driver for Microsoft Windows XP x32 from the Driver CD of my purchased laptop.

How can I change my power settings or BIOS settings in correct configuration?

 

Well tbh, it's unlikely to be due to BIOS (unless you made any changes there at the time of the reinstall?). To check the settings in Windows, open up the Control Panel, choose to view the page in Classic View then select the Power Options icon. This will then load a page showing you the three pre-configured power schemes. Choose to change plan settings (for whichever one is currently selected) and then select to Change advanced power settings. On the box that pops up, have a look for processor power management and then you should be able to change the minimum processor power or something like that.

 

Thanks for the reply.

I can't find Change advanced power settings.

I'm using Microsoft Windows XP x32 SP2.