http://talkplaystation.com/ps3s-ram-and-rsx-explained/

There has been a lot of talk about the Playstation 3’s Random Access Memory (RAM) vs Xbox 360’s RAM, saying that the 360 has more RAM to work with etc. Here’s an article to explain the situation of its RAM.

Just so you know that the PS3 has 512MB of RAM (256 for video and 256 for system). The Cell chip has 256MB of completely sharable RAM, the GPU has 256MB of dedicated RAM. Now the key here is what type of RAM it is.

The Playstation 3 has 256mb of GDDR3 at 700mhz  and 256Mb of XDR at 3.2ghz. So what exactly is XDR ram? Here are some of the highlights:

XDR makes PS3 super effiecient
XDR aids in faster cache mapping, both direct and indirect
XDR ram works by a pointer to pointer technology and needs very small buswidth for execution
XDR is not just faster than GDDR3 but it is much more efficient
XDR RAM works by breaking down data into several packets which prevents data loss and exceptions

The Rambus XDR™ memory architecture is a total memory system solution that achieves an order of magnitude higher performance than today’s standard memories while utilizing the fewest ICs. Perfect for compute and consumer electronics applications

The PS3 has two times as much cache at 2x the speed, making it way faster for direct/indirect mapping. Not only that but it has 512k of L1 cache + 1.7m of L2 cache for the 7 spes. The PS3’s GPU, RSX was made to work with the Cell processor, it is not some GPU they took and slotted in. It is made to be compatible with the Cell.

More RAM does not mean a faster system it means more data can be stored in a fast access area. Games don’t always need 512mb of RAM.

The RSX can freely use as much of the 512MB total RAM that the PS3 has because the Cell doesn’t need much RAM because its fast enough. And the fact that the PS3 has XDR means that it has faster access to data files.

A lot of people are saying that the RSX only has 256mb of RAM, whereas the 360’s GPU has 512MB of RAM. To make it sound a bit simpler, here’s the real deal. The PS3 has it’s RAM in two separate parts, 256MB for the RSX and 256MB that can be used be either the Cell or RSX.

cheers!

Vowiski
Why not let the games do the talking?

And so far, the Xbox 360 has come across as having similar and often better graphics than the PS3.

So, now you've finished MGS4, what next?