In a startling new discovery, Digital Foundry reported with much surprise at their own findings that the Sony PlayStation 4 game console reserves as much as 3.5 GB of the available 8 GB GDDR5 RAM for the OS, leaving only 4.5 GB for the game developers to use. Digital Foundry further detailed that 1 GB of RAM is placed under "flexible memory" as per Sony's internal PlayStation 4 documents.
We are as much baffled as others as to why Sony would reserve more than 3 GB of RAM to run the OS. Sure there are many background processes running. Features such as automatic gameplay recording for up to 15 minutes, seamless switching between the game and the OS and other goodies, we still don't understand how all of this could eat up 3 GB of RAM.
While game developers are themselves wondering how to best use all of the 5 GB of available RAM, its always good to have more in reserve than fall short, maybe in the future when the developers finally figure out how to use all of the available system resources (and optimize it accordingly).
Just so you remember, the PlayStation 3 OS ran on barely any amount of RAM, and by barely we mean just a couple dozen megabytes.