Mark Cerny Explains How the PS4's 8 GB GDRR5 RAM and Bus Work and Why They Were Chosen

[ethomaz]

Pemalite said:

You're right on that you can't just "drop" in GDDR5 memory with the Xbox One, the memory controller (Which is part of the CPU these days) needs to support it, hence the entire APU would need to be respun in order to accomidate GDDR5 memory.

As for the PS4 CPU being "slightly faster". - Well, DDR3 has 20% lower latency over GDDR5 (10ns vs 12ns), so that's going to be a slight (And possibly only?) advantage the Xbox One has over the PS4, which should benefit the Xbox's CPU performance, especially when there is a cache miss.

In the end though, it won't matter, the PS4's and Xbox One's CPU's are incredibly slow to begin with, the advantage the PS4 will have is that it can offload some CPU tasks onto the GPU.

Also, I think you meant DDR3 not GDDR3, there are some differences between the technology.

The latency comparison is not true.

Like I explained before the latencies is defined by the memory controller and I give even a example where the GDDR5 have lower latency than DDR3 (GTX 680 vs A10-5800k).

You don't know what the latency of GDDR5 on PS4 and what the latency of DDR3 on Xbone... so we can't make any assumption here.

And 10ns vs 12ns theoretical (in pratical the latency is ~40ns) won't give you noticeable difference in CPU taks.