New technology to put computers in a doze could mean energy savings of 60 to 80 per cent, say computer scientists at UC San Diego and Microsoft Research.

They've created a plug-and-play USB hardware prototype for Windows PCs that induces a new energy-saving state they call 'sleep talking'.

Normally, PCs are either awake (where they consume power even when not in use) or asleep (where they save power but are unresponsive to network traffic). The new sleep talking state provides much of the energy savings of sleep mode and some of the network-and-Internet-connected convenience of being awake.

A green dream

The Microsoft team built a small USB-connected hardware and software plug-in system called Somniloquy that allows a PC to remain in sleep mode while continuing to support instant messaging applications, VoIP, background web downloads, peer-to-peer file sharing like BitTorrent, and remote access.

Somniloquy is basically a very small, low-power computer that impersonates the sleeping PC to other hosts on the network, only waking up the PC when necessary. For example, during a movie download, when the flash memory fills up, Somniloquy will wake up the PC and transfer the data. When the transfer is complete, Somniloquy puts it back to sleep.

The current prototypes work for desktops and laptops, over wired and wireless networks, and require no changes to the PC, routers or other network infrastructure. The researchers say that Somniloquy consumes 11 to 24 times less power than a PC in idle state, translating to energy savings of 60 to 80 percent.

In the future, Somniloquy could be incorporated into the network interface card of new PCs, which would eliminate the need for the prototype's external USB plug-in hardware.