Eurogamer
UPDATE: A new source familiar with the matter has provided additional information to Digital Foundry that confirms only 4.5GB of the PS4's 8GB GDDR5 memory pool is guaranteed to game developers right now, while also clarifying how the PS4's "flexible memory" works in practice.
In real terms, an additional 512MB of physical RAM may be available in addition to the 4.5GB mentioned in the SDK. Flexible memory consists of physical and virtual spaces, and the latter introduces paging issues which impact performance. In our original story we combined them together.
For practical game applications, the correct figures for this story, as we understand it now, are a guaranteed 4.5GB for development and a further 512MB from the flexible pool. We have updated the headline accordingly.
http://www.eurogamer.net/articles/digitalfoundry-ps3-system-software-memory
