[QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="HarakoMeshi"][QUOTE="FrYGuY101"][QUOTE="NickLikesWii"]Remember Sony talking about how the PS3 can generate excellent real-time graphics using only the power of the Cell, with no GPU at all? They showed up demonstrations of this at E3.FrYGuY101
You would have an arguement if the Cell could directly read/write from the GDDR3. When I first started reading into the PS3's architecture, I thought that would be the case, and the Cell would be able to just dump the SPEs to help with the graphics computations. Unfortunately, the Cell has to go through the RSX's bus to read/write from the memory, and that means less resources for the RSX. Sigh, could've been so shiny. The SPEs don't directly read the GDDR3, it is inefficient to do that. (It's possible to do but very slow). Instead the GPU must 'fetch' the data from the Cell. So the SPEs must first dump the data to XDR memory and then the GPU reads them directly from there or transfers them to GDDR3. The transfer rate when GPU is in control is very fast. That's my point. Dumping it to XDR, then the GPU reading and writing to GDDR3 is inefficient in itself. If the SPEs could dump to GDDR3 directly without going throught the GPU bus it'd make the setup a lot more effective. That is true, but processing polygons on the cell is not 100% required it is only a bonus, and more than likely geometry on PS3 games would be split between XDR & GDDR3 anyway since the memory is not unified. The GPU will happily process data from both memories, in fact acieving even higher bandwidth by doing both in parallel. A developer would organise some geometry & textures in GDDR3 and some in XDR. Compared to the 360, 360 has an advantage of unified GDDR3 memory that everything can read from everywhere, and also a disadvantage that bandwidth is completely shared between the GPU and 3 CPU cores. If one hammers the memory the other will be starved. Also XDR bandwidth is much higher than GDDR3. One thing that I have experimented with on the PS3 is splitting frame buffers between GDDR3 and XDR. I put Z buffer in GDDR3 and color buffer in XDR. By doing this the combined bandwidth increased the memory bandwidth such that even the nastiest alpha blending did not slow down the GPU from its peak fillrate. Sweet huh? 2 memories = 2 sets of bandwidth to make use of. Yeah, I've heard that trick, it does sound pretty useful. Still, Sony should've ponied up for a point-to-point hypertransport interconnect, that way both the CPU and GPU could make use of both RAMs without having to resort to work arounds like going through the GPU bus, and the Cell's SPEs would be far more useful for preprocessing graphics. Yeah well the flexIO was supposed to be that kind of amazing interconnect but finally got an incredibly poor 16MB/s reading from GDDR3 because of some bug in the implementation. (thanks STI) But I still think they are very useful if not as useful as if they were glued directly to the GPU :D Sony already ponied up too much. I still wish they had made their Sony+Toshiba custom GPU, that would have torn apart the 360 to shreads. It had 256GByte/s EDRAM! The 360 *HAS* 256GB/s ED-RAM, which handles z-buffering, alpha-blending, fp10 HDR and 4xAA. It's a developer's dream, man...That is correct although the actual bus from GPU to the EDRAM daughter chip (the Smart Memory) is only 32GB/s. The daughter chip is able to utilise 256GB/s when doing 4x MSAA. Essentially 4xMSAA is free. This has the effect of smoothing polygon edges but does not work on things such as wire fences or other transparent things.  Those require SSAA which is then limited by the 32GB/s. (Still faster than the PS3 though).
The only limitation of the 360 GPU is having only 10MB EDRAM which is not enough to take advantage of free 4x MSAA at 720p resolution. That would require over 28MB of frame buffer memory (1280*720*8bytes*4) so the whole scene would have to be rendered 3 times to 3 slices of memory, thus making it 'not so free' - in fact slower than the PS3 can do it.
This is the reason PS3 can boast higher resolutions including true 1080p games. At 1080p a minimum of 16MB of video ram is required without any kind of AA. 64MB with 4X AA. The 360 would have to render between 2 and 7 passes to achieve 1080p while the PS3 can do it in one pass.
On the face of things the 360 GPU appears to have an edge over the PS3, but for 720p games with 4xAA it's actually going to be slower. "Oh oh", atomic lemming destruction. "pop, pop, pop, pop, pop, pop, pop....".
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