True, G71 doesn't look all that great in the game but it should be remembered that its running at something like 1024x600 on the consoles so its a drastically lower resolution that what those benchmarks are taken at. I also don't fully accept that its a solid 60fps on the console versions as there is too much variation when playing the game to allow that (i.e. an 8800 may average 80fps but it will still regularly drop into the 40's). I expect 60fps is more of a "most of the time" kinda thing. With most of the time equating to >50%. I can't prove it of course but it certainly wouldn't be the first console game to claim to run at 60 or 30fps but clearly run slower. One things for sure, to maintain a solid 60fps all the time the game would have to average about 100-120fps
There's a good chance that COD4 has a more console-like workload than PC games in the heyday of G71. It looks like the unified GPUs have a notable leg up on the older ones (if you recall R600 often has marginal gains over R580, as expected from the specs, but not here). You'll also notice the 7900GTX 512MB performing slower than the 2900XT 256MB, in case you still really believe your analogy.
Thats a good catch, in fact its one of the very few examples I have seen were the 2600XT does come out on top (and amazingly even the 8600GT). Its unlikely to be down to unified shaders though based on R580's performance. Perhaps something to do with branching capability?
Being indistinguishable in games doesn't really imply equality. It implies designing for good playability on the slower platform. If you could put G80 in any of these consoles, cross platform games would probably still run the same because that's how the game was designed.
Perhaps. However in light of any onscreen evidence showing either platform to be performing significantly better, and given how on paper they are fairly even GPU wise, there doesn't seem to be much reason to assume Xenos is significantly superior.
Granted, I would pick Xenos over RSX if it was a one or the other choice of which is better but I don't think its a cut and dry win. And of course, something like the GTX 512 is faster than RSX again.
A lot of those things can actually be faster on Xenos, believe it or not, in real-world situations. Not always, of course.
There's my problem. On paper, R580 is faster. On screen evidence, i.e. cross platforms games, tend to corroborate this and at the time of launch, even ATI said it was more powerful. I just can't swallow the idea of an older, theoetically weaker GPU being faster in the real world when all the evidence I see points to the opposite.
On the PC, I'd agree. For games primarily intended to be sold on the consoles, I bet plenty do. Your COD4 example, for one.
But thats just it. How many console games come to PC and won't run as good or better on an X1950XTX than the console from which they came? If there were plenty of examples then I could agree with this but i'm not seeing any. COD4 for exmaple, is averaging 41fps at 1920x1200 and 16xAF. Its would be a stretch to say thats not performing as well or better than the console version which runs at well below 720p (assuming identical levels of details are used, HDR format springs to mind).
The 1/2 to the daughter die is less of a problem than you think, as it's a narrow point in the data stream. Sure, for pixels with no AA and no blending R580 is faster, but often BW isn't a problem anyway. Enable those and add non-zero texture bandwidth and it's very possible to see Xenos on top.
Yes i'm sure there are definatly situations when the edram will help achieve things that wouldn't be possible on R580 but what i'm saying is its not just a straight 64GB/s < 256GB/s. There is the interface between the dies to be considered as well as the lack of compression on the daughter die. Isn't that something like 8:1 on the R580? Thats gotta have a major impact.
I'm sure each memory architecture has its benefits over the other, i'm just saying edram doesn't equal a clear and sweeping memory bandwidth win for Xenos.
When I say RV630 isn't performing up to par, I mean in comparison to R600, not to paper. The COD4 benchmark looks okay, but I haven't seen many recent 2600XT benches and only remember the launch. It was a bigger step down from the 2900XT than the 8600GT was from the 8800GTS, even though specs suggested the opposite would be true. There was something flawed about RV630.
I would have said it performs pretty much in line with its specs. 1/4 the ROPs, 1/2 the texture units, ~1/3 the shaders, ~1/4 the memory bandwidth.... if anything its amazing that it performs as well as it does
My point was that RV630 is not a good basis for you to judge ATI's architecture, even if you believe that R600 is (which it isn't).
For arguments sake then lets put RV630 aside and instead focus on R600. You say its not a good judge of Xenos and I agree its far from perfect but its also quite easily the closest architecture that you are going to get and its definatly in the ball park. R600 is a direct decendant of Xenos. ATI had ample oppotunity to study Xenos's performance in the real world and improve upon it. There's little reason to expect R600 to perform worse for a given number of execution units than Xenos and in fact I think its pretty generous to simply assume parity between them in terms of efficienty. In all likelyhood for a set amount of resources R6xx will be faster.
But anyway, on paper R600 averages around 1.5-2x more powerful than Xenos (ignoring efficiency improvements).
Is it really that unrealistic to assume that at Xenos would be
around 50-66% the real word power of R600? What better indicator is there? Unified shaders don't help Xenos in this comparison and in comparison to R600 in particular, neither really does the edram.
A) You are comparing to RV630, not R600/RV670. The former is not half the speed of the latter per clock, despite specs suggesting so.
As mentioned above, RV630 is actually much less than half the spec of R600.
B) It's not absurd, because problems happen all the time especially when you're late. NV30 was less efficient than NV25 in almost every way. The R6xx architecture was also designed to scale downward, resulting in a different organization of the ALUs and TMUs.
Well NV30 was a brand new architecture which bore little relation to NV25. Thats completely different to R600 which is basically an extension and enhancement of Xenos's architecture (the second generation unified shader architecture in ATI's words). ATI engineers would have to be pretty incompetent to actually re-design it to go slower
Anyway, I don't really think NV30 was inefficient compared to NV25. It was afterall much faster while also supporting DX9 (however poorley). Sure it was crap compared to R300 but it really did wipe the floor with NV25 for the most part.
C) Console workloads are different, and not just in terms of vertex/pixel load. There are things in Xenos that are probably not there in R6xx to address this.
But again, how are they different? A game is a game is a game whether you playing it on PS3, Xbox 360 or PC. All may have different ways of getting that game onto your screen but the task and the end goal are identical in each case. Pixel/vertex loads for example are no different in the PC version of COD4 than the PS3/360 versions. Nore is any other aspect of the game as far as I can tell.