Intel demos Panel Self-Refresh power-saving tech

DisplayPort screens store their own picture

IDF 2011 Intel today demo'd an interesting screen-based power-conservation technology: Panel Self-Refresh (PSR), part of the Embedded DisplayPort (eDP) standard.

PSR incorporates a frame buffer into the display's own electronics, allowing it to refresh the screen's pixels directly rather than continuously requesting image data from the host device's GPU.

This means the GPU isn't being woken 60 times a second to re-send the current frame buffer's contents over the DisplayPort bus to the display.

The GPU needs only exit a low-power, sleep state when the contents of the main frame buffer changes. Even if the screen is changing 30 times a second, there's still an opportunity to keep the GPU asleep while image data is read from the display's own buffer.

The tech requires the on-screen picture to be monitored for static images. Intel demo'd it using a photo slideshow app. During picture transitions the graphics core needs be brought back to life but once the picture is no longer changing, the GPU can be allowed to stay asleep, reducing power consumption.

As long as the screen is being powered, it will continue to show the image, even if the connection to the GPU is cut. Not that that should happen in a laptop, but it clearly demonstrates the display's ability to operate without a picture source.

PSR isn't new. It was incorporated in eDP back in February 2011 when DisplayPort overseer Vesa published the eDP 1.3 specification. But even then, Vesa said the tech won't make its way into notebooks and netbooks until 2012.

Intel will be supporting the tech in its 'Ivy Bridge' processors, which connect their on-board GPU to display sub-systems over an eDP link.

Intel's PC chief, Mooly Eden, said he expects PSR to be standard on notebooks within two years. ®

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