Despite rumors to the contrary, Sony’s PS4 will not be using more than 5.5GB of its GDDR5 8GB RAM for gaming. According to Eurogamer’s Digital Foundry, the console is limited to 4.5GB allocated directly to games with another 1GB that can be used by developers depending on what the console OS needs to do.
Current PlayStation 4 dev kits have a “Game Memory Budget Mode” in the debug settings featuring two options: normal and large. The normal mode setting confirms that 4.5GB of memory is usable for game applications. The large mode increases this considerably to 5.25GB, but the docs are clear that the extra RAM here is only available for application development, presumably in order to house debugging data. From what we understand, the extra gig of flexible memory appears to work in addition to these allowances.
Unfortunately for fans of the PS4, this brings the specs closer to parity with the Xbox One. The difference of GDDR5 memory in Sony’s console versus the DDR3 in Microsoft’s could still be a key factor for developers.