LG in it's new flag ship model G2 have Graphic RAM, or GRAM, helps in reducing the display’s energy usage by up to 26% on a still frame,it also helps to increase the overall usage time on the device by approximately 10%. While the numbers sound good, the technology that achieves the same seems a bit fuzzy.

Graphic RAM is the nomenclature that LG has adopted for a technology called Panel Self Refresh.Normally, the GPU of a smartphone or tablet sends the frame image to the display panel 60 times per second. This includes things like an ebook, where the image itself is not moving. And this frame image is sent again and again, which leads to a considerable expenditure of power. When the user switches to some other data on the display, the new screen is rendered by the GPU, which is followed by the process being restarted all over again. While games and videos require constantly undated frames, for surfing the Internet or reading ebooks, there is a considerable period of time where everything is static, where the display is updating the same frame image.

This is where GRAM comes in. The technology adds a memory cache to the display panel. This memory cache is used to display the same frame over and over again without the need for the GPU to get involved. Thus, when the CPU and GPU detect that there is no change to the displayed data, a command is sent out to the display panel, which tells it to grab a screen capture of the current frame and to keep it displayed unless instructed otherwise. In the interim, large bits of the Soc, including parts of the GPU, can shut down. This helps to save valuable amounts of energy.

The real time application of this technology spans in the seconds and the user will not really notice any difference at all. But in the system, different parts of the SoC will be shutting down and firing up, similar to how the idle cores on a dual-core or quad-core CPU shut down and start up when needed.

And the energy saved due to this, according to the company, is significant. The data also shows just how much power the SoC uses up just to refresh the display. And it seems like the energy expended on static displays is considerable. It should be noted that the display panel itself will continue to consume the same amount of power as it still needs to refresh 60 times per second. The change comes from the fact that the data is now being provided from inside the display panel circuitry.