Personal thoughts…

Tech, Hockey, and random thoughts…

Console examination #2

I've already taken a look at the Cell vs XBox 360 PPC combo, so I figure it's time to examine the graphics side of things.

First the wrapup: The PS3's Cell should be a decent amount more powerful on paper, but it will be incredibly difficult to program for (Though the XBox 360 isn't exactly easy to program for itself).
I suspect the PS3's performance advantages will take a much longer time to come to fruition then the XBox's advantages over the PS2, and it's possible though unlikely the Cell will never be sufficiently adopted enough to truly take full advantage of it's power.

On the whole I'd be looking at the XBox 360's processor to comparable to an Athlon64 X2 4200+ (2X 2.2GHz/512KB Athlon64), on paper at least the Cell should offer greater performance then the Athlon64 X2 4800+ (2x 2.4GHz/1MB Athlon64) though programmer difficulties will slightly nullify that.

Compared to X86 desktop processors we should see high end desktop processors in the Athlon64 X2 available before the Xbox360's launch that can match the respective consoles processors.

As a side note- the Cell processor would with only one truly general purpose processing core will be blown away by the XBox 360 and modern X86 processors on general purpose code but that doesn't really matter on a console.

Now onto the GPU's:
XBox360: Based off the R600 with unified Pixel/Vertex shaders, and 12 pipelines with 4 ALU's per/pipe @ 500MHz it should offer shader performance a decent margin above that of the X850XT PE.
Yet with only 8 Raster Ops (ROPS) it's pixel throughput is only very marginally better then current mainstream PC graphics cards and well below the X850XT PE. The GF 6600GT in fact, can offer stencil fillrate comparable to the XBox GPU, and nVidia's high end cards nearly twice as powerful in that respect.

PS3: nVidia RSX, based on the G70 core.
It would appear then the nVidia RSX is similar to two GF6800Ultra's in SLI in many respects.
Based on the currently available data on performance specifications/300M transistors on an 8layer 90nm process/550MHz core clockspeed I'd say it's most likely that the RSX has 24 pixel rendering pipelines. The number of RasterOps is hard to guess at, but I'm leaning towards saying that the RasterOps are not decoupled from the pixel pipelines.
if the above is accurate the PS3's GPU should offer vastly more pixel/texture fillrate then the XBox360's graphics core. Unlike the Xbox360, the PS3's GPU still uses dedicated pixel/vertex shaders.
It would seem that the RSX should offer slightly more geometry throughput then the regular GeForce 6800 per clock/pipe. On the whole your probably looking at shader performance somewhere around 20% greater then that of a pair of GeForce 6800Ultra's in SLI.

Comparison:
The pixel/texel fillrate advantages of the PS3 should be partially mitigated by the XBox360's 10MB (512bit memory controller) EDRAM that could be used as a cache for the graphics processor. The Xbox360's graphics can access the 512MB of system memory via UMA (Unified Memory Architecture) with a bandwidth of 22.4GB/s.
The PS3's graphics core has 256MB of dedicated memory and can render directly to the 256MB of system memory(25.6GB/s bandwidth) in a similar fashion to nVidia's TurboCache that we've seen on their desktop GeForce 6200TC graphics cards.

On the whole it would seem the PS3 should offer a solid advantage in terms of pixel/texel output at the 480i/720P resolutions I suspect will be the norm for next gen consoles, but I'd suggest the XBox 360 should offer comparable shader/geometry performance.

On the whole, I'd look towards the XBox360's graphics processor to offer performance similar to a pair of 6800Ultra's in SLI while the PS3's graphics processor should be beyond that by a small margin.

Compared to PC graphics cards I'd say we should see high end graphics cards comparable to the PS3's GPU at roughly the same time the XBox360 launches. Upper midrange graphics cards should marginally less then that level of performance a few months after the PS3 launches at which time high end PC graphics cards should be a fair margin beyond it.

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May 17, 2005 - Posted by | Console Examination

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