First introduced with OS X Mountain Lion, Power Nap is a feature that, when your Mac goes to sleep, it still allows it to get things done. It periodically updates Mail, Contacts, Calendar, Reminders, Notes, Photo Stream, Find My Mac, and Documents in the Cloud. When your Mac is connected to a power source, it downloads software updates and makes backups with Time Machine. While all that updating is going on, the system sounds are silent and no lights or fans come on, so nothing disturbs you. And when your Mac wakes up, it’s good to go.
While Apple’s Power Nap feature is currently limited to a small selection of MacBook Airs and Retina MacBook Pros, it appears that some iMacs utilizing flash storage or Fusion Drives may be able to take advantage of the technology when Mavericks is released.
In the screenshot below, the latest iMac (released in October 2012) is shown running Power Nap. The model includes a Fusion drive, first introduced alongside the iMac, which combines flash storage with a standard hard drive.
Because it runs in the background, Power Nap requires a solid state drive to function. At this time, it is not clear whether additional products, such as the Mac mini (which also has a Fusion drive option) will be able to access Power Nap as well.
Mavericks also includes a separate feature called App Nap, which is designed to extend battery life when working with multiple apps at one time by limiting power to the apps running in the background.
OS X Mavericks is expected to be launched to the public in late October. The Golden Master, which is the final version of the software that will be provided to the public, was seeded to developers last week.