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  1. #1
    Starlight Guest

    PlayStation 3's 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 is an article to explain the situation of its RAM.

    Just so you know, 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.

    More PlayStation 3 News...

  2. #2
    Pino84 Guest
    Thanks for all the info, and do you know if there is a difference in the 40gb ps3.. or if they are ever able to run ps2 games?

  3. #3
    Techni Guest
    Quote Originally Posted by gfather View Post
    but again the 360 can have more memory for the graphics
    No. 360 has the exact same, only all of it is shared. PS3 has 256 MB of dedicated/faster vram, and 256 MB of shared (with the CPU) ram

    Shared is inferior to dedicated.

  4. #4
    sanmadjack Guest
    Quote Originally Posted by Pino84 View Post
    Thanks for all the info, and do you know if there is a difference in the 40gb ps3.. or if they are ever able to run ps2 games?
    All the PS3 models have the same amount of RAM, and the RAM issue has nothing to do with PS2 compatibility. As for 40gb running PS2 games, it would require Sony writing an emulator for the PS2 GPU, which doesn't seem to be something they're too keen on doing.

    Quote Originally Posted by gfather View Post
    well the 360 has 512 for system and 256 for graphics, so it can take 256 for graphics and still there is 256 for general stuff, so in all of all preformance 360 still has a better advantage.
    This is not true, the 360 only has 512MB of RAM, not the 768MB you are implying. The 360's hardware is documented very clearly at http://en.wikipedia.org/wiki/Xbox_360_hardware

    Additionally, as you put it "take 256 for graphics and still there is 256 for general stuff" is exactly what the PS3 does, so how exactly does the 360 doing that make it "has a better advantage"?

  5. #5
    asandhu Guest
    so does the fact that the ps3 has dedicated ram make it in any way better than the 360, or does it not make a difference?

  6. #6
    ptit6sky Guest

    The fact that the memory isn't shared make a difference, because, the RSX will always have a minimum of 256 MB of memory because it's dedicated, whereas if the RAM was shared, RSX would have to share memory with CPU etc ....

    In conclusion dedicated RAM is better than shared one.


  7. #7
    dude2193 Guest
    Quote Originally Posted by ptit6sky View Post
    In conclusion dedicated RAM is better than shared one.
    True but even better ontop of the dedicated 250mb for the RSX the cell can chare any of its un used ram for use with graphics. Plus on another note some developers i.e Guerrilla use the cell for (some) graphics processing.

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