But then why don't PC's use all GDDR5 instead of DDR3 and 5? I honestly don't know. Everyone seems to act like 8Gb of DDR3 is going to cripple the One but my PC has that and it seems to do just fine!
There's a reason why all performance graphics cards only use GDDR5. Higher resolution textures require huge amounts of RAM bandwidth. In order to be thrown around at high FPS.
DDR3 is better at general purpose software code, and data. Quicker access for frequently changing data.
That pretty much sums it up.