| Procrastinato said: I believe the closest PC GPUs, if anyone wants to do any comparisons online, are the ATI Radeon X1800 XL (for the 360), and the NVidia 7800 GTX (for the PS3). Not 100% sure how close those are to the "real thing" though. I would like to point out that X360 games, since they always use the same GPU, can make much better use of the flexible pipelines of the GPU, than your typical PC game can with plain ole D3D 9/10. You'll probably notice that, in the vast majority of comparisons between these two cards online, the NVidia card is the clear winner, except in a few cases involving AA. Keep in mind the special mojo of having just that one architecture to work with, though. Its a bigger deal than you might think. Sadly, with regards to the topic, most games fall into the generic usage category, and not into the "we have the whole scene in memory, and there's not much going on, lets use some serious textures!" bucket that RB/GH fall into. |
Both are pretty different with regard to design, the Xenos for example relies on EDRam, which is a significant bottleneck at higher resolutions while the PC variant unlike the Xenos has dedicated main graphics memory. The disadvantage of this design shows by having 720p graphics combined with AA and (significantly increasingly so) upwards. The optimal 360 resolution seems to be 600p with AA (for demanding games at 60 FPS), 640p without AA (but with wide range HDR like Halo 3 @ 30 FPS) or 720p with AA at 30 FPS.
Apart from larger than usual cache, the RSX mainly distinguishes itself from the PC graphics chips with regard to being adapted to take advantage of the Cell's SPUs and potential usage of the XDR memory simultaneously with its dedicated main graphics memory. Using SPU resources can result into up to ~50% additional graphics performance (taking workload off the GPU) according to developers.
For example with regard to Super Stardust HD (a game with over 20,000 moving objects and over 75,000 particle effects on screen at once) is drawn 60 frames per second at 1280x1080 (1080p resolution, upscaled to FullHD):
"Currently we do not use SPUs to pre-process the geometry for RSX — that will make a major difference. I estimate that we can further boost the graphics performance by 50%."
I think when everything is said and done (full optimization), the PS3's optimal resolution is probably 1280x1080 with AA at up to 60 FPS for demanding games like Gran Turismo 5. I think this resolution provides the best trade off with regard to perceived details and rendering performance, the vertical resolution being the most important for human perception, going higher with the horizontal resolution vs upscaling will probably not yield real perceptual gains, yet this resolution will still contain full detail when scaled down to 720p. Actual nearby texture detail may be well lower though, like is the case with all PC games running at such resolutions. I will have a more informed opinion with regard to this when I have finished Uncharted 2 (judging Blu-Ray/harddrive streaming quality), God of War 3 (usage of procedural textures) and maybe more relevant from a technical perspective a game like WarDevil. 
