Why your laptop may run slower on batteries than on mains

It may be that your Laptop PC, either PC or MacBook (Intel based) will run slower when running on batteries than on the mains. This is because of Intel SpeedStep or Intel TurboBoost technology.

The main purpose of Speedstep or TurboBoost is to reduce CPU clock speed when the laptop is running in powersave mode, or on battery power, so as to generate less heat and increase battery life. Some desktop processors also have this feature, but as desktops dont have batteries, this feature is less noticeable than on laptops, as desktops are always on mains power.

When SpeedStep is enabled, your processor will idle when not performing CPU intensive tasks, then the speed will ramp up when you throw more tasks at it, such as having many web browser windows open, or running a few programs at the same time, known as Multi-tasking.

SpeedStep can sometimes be disabled in your laptops BIOS< if PC, but it may not be recommended as it may casue the fans to come on more often or overheating if the laptop is old and the fans are clogged with dust. The BIOS settings will be usually under the Power Save menu, but please refer to your user manual for instructions, as not all BIOS’s are identical.

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Mike Gisbourne is an IT Professional/System builder from the UK with 20 years experience of PC building. Building PC's since 8086 days and Windows 3.1/95. Mike specialises in PC hardware, server administration, hosting. He is also a musician, keyboard player.