Facebook's figures say that just eight per cent of the billions of images it holds account got around 85 per cent of traffic at any given time.
By keeping that data readily available a fast data centre and the rest in a relatively slow-running facility, it aims to slash its energy costs, the Telegraph reports.
According to the paper, the new cold storage facility will join two existing data centres in Prineville.
Each is capable of storing an Exabyte of data, the equivalent of 250 million DVDs full of information.
A report by the Oregonian said that in the new data centre, more hard drives would be connected to each server computer.
It will mean a photo will take marginally longer to access but increase efficiency, as servers consume a lot of electricity to carry out their computing work, it added.