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Confirmed: Rsx Is “nv47” Based

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#1 KAGE360


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Posted 03 April 2006 - 09:00 PM

It’s long since been known that NVIDIA will be providing the graphics processor for Sony’s Playstation 3, otherwise known as the RSX "Reality Synthesizer". While the expectation has been that it would be of a similar configuration to NVIDIA’s G70 chip, powering the GeForce 7800 series, a precise answer as to its composition has never been given before. However, accordingly to an article at watch.impress.co.jp, which has slides from Sony’s GDC briefings, RSX is confirmed as being “NV47” based.

NV47 is actually the previous codename for G70 – in fact development tools still list G70’s codename as NV47 rather than G70. The graphics slide also highlights that RSX has 24 texture units, which is consistent with G70. Given the architecture of NVIDIA's G7x series, this indicates that RSX will also have 24 fragment shader pipelines with two ALU’s per pipeline.

This may also give some clues to why NVIDIA sought to release G71 in the configuration that it has, with the same pipeline counts as G70, rather than opting for a chip with more pipelines as the popular speculation indicated prior to G71’s release. It is likely that much of the 90nm optimisation undertaken with G71 was to cut down on duplication on the work being carried out on RSX.

The other, known, primary differences between G71 and RSX is that the PC's PCI Express interface will be replaced with a FlexIO interface for communication to the Cell processor, and RSX will only use a 128-bit bus, rather than a G71's 256-bit interface. Given the memory bandwidth difference between RSX and the PC versions, it begs the question as to whether RSX will retain all 16 of G71's ROP's. With the previously stated 700MHz memory speeds for RSX it will end up with the same local bandwidth as NVIDIA's mid-range GeForce 7600 GT, but also has to contend with twice the texture consumption (when sampling from graphics RAM) and pixel processor capability - it may not be much of a surprise if RSX enables 8 ROP's as opposed to the full 16 of G71.



laugh.gif "Reality Synthesizer" laugh.gif

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