With all the rumors around it seems the ps4 will use an amd apu. my guess is it will use an amd A10-5800k and a 7850 gpu. this would keep cost and power consumption down. it would also provide a decent enough increase in visuals over the ps3, while being easy for 3rd party developers to use and make games for. As for the amount of system memory, 4gb should be plenty since its only a console.