Now I think about the Microsoft DDR3 choice and Sony GDDR5 choice... I have on theory.
- Microsoft always wanted to use 8GB RAM in Nextbox and when they created the project the available memory module for GDDR5 was 2Gb (256MB)... so they needs 32 chips to make a 8GB console with GDDR5... so the alternative was to use DDR3 and try to made a lot of custom changes to added cache/buggers RAM (eDRAM or eSRAM) and fixed units to avoid all the bottleneck created by the use of DDR3... so the Nextbox design and project was made using DDR3.
- Sony never wanted to go with 8GB RAM so they can use GDDR5 in their project because with 16 chips you can have the 4GB RAM... so Sony made the design and project using GDDR5.
- After a lot of complain about 4GB RAM from developers and the fact the GDDR5 4Gb (512MB) was available in early 2013 for mass production... Sony decided to change the 16x GDDR5 2Gb modules in the project to 16x GDDR5 4Gb modules... so the design/project was not changed just the memory module have different density.
That was what I think happened... Microsoft can't change the DDR3 thing because it needs a new design for memory controller and change all these stuffs about Data Moves and eSRAM... in fact to change from DDR3 to GDDR5 Microsoft needs a design/project to Nextbox.
Sony just have the luck to choose GDDR5 and the release of the GDDR5 4Gb modules happened in the early of this year.
I think if the GDDR5 4Gb modules was available in early 2012... Microsoft coulb be choose GDDR5 to fit their 8GB target.
