You've been disputed on this count a number of times by actual game developers. Face it, you simply have no clue. MS went TO eDRAM because unified memory was a troublesome design in the original xbox, as was it in the N64 before that. It's cheap and easy to design, but performance is not particulary consistent as MS (re)discovered. eDRAM may be limited in space, but performance can be there in oodles. Transparencies forcing read-modify-write accessses kills performance on any design using external RAM, but PS2 with its triple-ported memory barely slows down at all. You could do 20 fullscreen smoke polygon layers on top of each other running at 60 frames/sec and you'd never notice it framerate-wise. That's the power of eDRAM.