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Thursday, December 22, 2005

Sony PS3 Graphics, there's more to it

Sony PS3 Graphics, there's more to it

"Ok, yesterday one of our readers informed us about an inaccuracy in one of our articles. Although his comments seem to be correct, another reader seems to disagree. So to be honest, I guess we're all lost and we'll just have to wait and see. But I couldn't spare you from the interesting read from our reader. It contains quite some information regarding Nvidia vs ATI's graphics cards in the next-gen console wars.


Just a few notes on your reader's comments published in this article..

"The fact of the matter is, is that Nvidia taped out the RSX months ago"

NVidia's non-recurring engineering revenue from Sony for RSX extended until Sept/Oct if not later - that is to say, they were still working on the design up until then. It only taped out perhaps a month or two ago. Xenos - X360's GPU - taped out last year. Not that tape-out time tells us much about relative power..

"The Xenos has unified shader architecture that the RSX does not, and as a result, the Xenos may actually turn out to be more powerful than the RSX."

Unified shaders do not necessarily provide any more power. It's just a new way to arrange power. In terms of raw horsepower, RSX beats Xenos quite handily - floating point power is greater, shader ops are higher, it's clocked faster, higher fillrate etc. Xenos's claim to fame is that while it has less of a punch, it should be used more efficiently, but in a closed box such as a console, such concerns are somewhat mitigated since a dev can hunker down and get the best out of ANY chip. Xenos is also the first implementation of a new architecture - not always a good thing, and we've seen suggestions of some sacrifices on the part of devs. For example, Inis, the people making the nFactor2 engine have suggested that Xenos has relatively little texture cache and so forth, compared to nVidia chips, in order to provide more transistors for the control logic for the unified shaders, and this forced them to break up work into two shader passes that can be done on one on a nVidia card. More enticing than the unfiied shading in my opinion is the eDram, which if used properly will give Xenos an advantage with framebuffer operations thanks to its large internal bandwidth. But on the flipside of the coin, PS3 should always have more bandwidth to feed the CPU, and for the GPU for non-framebuffer tasks (texturing, vertex fetch etc.).

"We already know that the Cell's architecture does not lend itself to games and graphics processing"

Pure nonsense. This guy has obviously not been paying attention to IBM's work with raytracing and rendering on Cell for example (or The Getaway demo which was apparently rendered only using Cell) and too much time reading Major Nelson-style ramblings. If you simply listen to what developers are saying they are using more CPU power for, Cell starts looking exceptionally suited for games. Most devs seem to be using extra cores for physics, animation, particle systems, graphics, audio, fluid/hair/cloth dynamics - these are the things which are most compute intensive, and these are the things the SPUs in Cell are really good at. As good, if not better than a conventional core, and there are 7 of them there in addition to the PPE. If you don't believe me, look up Tim Sweeney's comments about Cell on - basically he says that the things SPUs aren't suited toward only take a small proportion of execution time anyway, and can be easily accomodated on the PPE. Or Crytek's comments about potentially achieving a linear speedup across the SPUs. Cell is a clear and large advantage for PS3 when it comes to games, there's no doubt in my mind." [more]

Anonymous Frost (Lincoln G.)
I dont think you could really compair PS3 specs with other game systems, or I should just say Xbox 360. Alot of People dont really know but the say the pipelines in the RSX, 1 of RSX's pipelines are about the same as 2-3 of the graphics card for Xbox360 pipelines.

I was reading on GameSpot that Sony didn't want to give there full specs because people would get the wrong Idea, and think oh if theses are there specs well just a bit better but nope. Like I said you would have to count each spec for Xbox 380 and then PS3 then double or triple some of PS3 specs. If you dont belive me check it out at, And for those of you who already know I was just says no harm done.  

Anonymous Anonymous
from what I've seen, it's not so much that cells are low powered when used for gaming, more that they are absurdly difficult to program for.

The example given is to use different cores to do different graphical effects, physics and the renderring. However a number of these require results from the other cores before they can perform their tasks. What do you do when the Core needs a result from another and it isn't ready yet? Have it sit around and do nothing? Have it perform another task and risk synconisation problems? These are very tough things for coders to consider.

This kind of multitasking is made even more tricky by the fact the cores share bandwidth and a large portion of the cache is shared.  

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