Why Xbox One Will Catch Up To Playstation 4 in Performance.

[mine]

Oh. The PS4 has GDDR5

Has anybody noticed that there is NO computer up to date which uses ONLY GDDR - even not those machines where "money doesn't count" ?

So - WHY is that? DOES GDDR HAS SOME SERIOUS DISADVANTAGES?

Yes. Because it is a special type of RAM TAILORED for GPUs - big latency but you can read and write at once.

DDR RAM is made for CPUs - low latency and you can read OR write at once.

Now lets investigate further why GDDR only is a bad idea on a CPU like AMDs Jaguar - those cores were designed with netbooks in mind. Of course they have doubled the number of cores to a total of eight so its raw compute power doesn't look that bad - this year...

But AMDs Jaguar lack a L3 cache and its L2 cache isn't that big too. If a core has a cache miss chances are big that the core has to wait longer for data on a PS4 than on the Xbox One. Thats where RAM latency comes into play.

CPUs favor small chunks of data and they need them fast.

GPUs need big chunks of data in parallel but they can wait a bit longer...

This might be the reason why Killzone fails to deliver true 1080p in Multiplayer: if the network code destroys to often the caches the cores have to wait and so these parts can't be as optimized as the single player code...

People are tempted to overlook such technical details and favour a simplified "expensive is better". But as already written - if this would be the case ALL high end servers (POWER, Sparc) would ship with GDDR instead of DDR . The opposite is the truth: DDR is better for CPUs and GDDR is best for GPUs. And to "glue" both together it's best to use something ultra-fast like EDRAM or ESRAM.