Windows 7 Destroys Vista on Battery Life!

If a notebook runs Windows Vista, it will run Windows 7 and it will get better battery life, promises Gabriel Aul of the Windows Performance team. But PC manufacturers and device suppliers are also going to have to do their part to make a big difference to power consumption on new notebooks.

What Microsoft can do is make it easier for components in the system to go into low power mode when the system is idle. Some of that is ‘managing’ components: Windows 7 ‘parks’ CPU cores that aren’t needed, finally implements the ‘slumber’ feature on SATA drives, powers down USB ports and controllers more aggressively and even puts your Wi-Fi card to sleep if it’s turned on but not connected to a network.

Reducing the power draw

Microsoft has also changed its thinking about the system timer; in Vista this is set to 1ms, in Windows 7 it will be 15ms, which reduces the power draw by 15 per cent. General performance improvements like reducing the amount of disk activity involved in reading from the registry and starting services on demand rather than running them in the background will also improve battery life.

That applies to all software: a Vista system running ten services that come with installed applications uses 6 per cent of the CPU even when the PC is idle, compared to 1 per cent for a clean Vista installation. An extra 5 per cent of CPU utilization translates into around 4 per cent less battery life, so Microsoft is encouraging software developers to use on-demand services.

Windows 7 notebooks won’t wake up from sleep for applications that use ‘wake timers’ (except for the timer that wakes the system when the battery is so low the PC needs to hibernate). Open files from a network and CPU utilization won’t stop the screen turning off, the hard drive spinning down and the system going to sleep when you haven’t used the PC in a while; Windows 7 will only check for user input and applications like Media Center recording a long TV show. The screen will also dim to save power before turning off.