[trinibwoy]

Originally Posted by Uttar

Words of wisdom. Someone give this man a cookie...!

Assuming that's the case wouldn't AMD (forcing myself to accept it!! ) be terribly concerned with Nvidia's possible advantage if they should decide to move to high speed GDDR4 on a 384-bit bus. That same 1.4Ghz memory is gonna give them 134GB/s of bandwidth. 1Ghz gives them 96GB/s.

What's going to happen next summer when Nvidia's $350-$450 card is rocking a 320-bit bus with some el-cheapo 1Ghz GDDR4 and 80GB/s bandwidth?

[Apple740]

I want to see some "leaked" Ati slides where the R600 is ~40% faster than the 8800GTX in Crysis@DX10.

[trinibwoy]

Why not just make them yourself? They'll be just as relevant / believable

[Rangers]

So I was thinking, what kind of specs does R600 need to beat G80, now that we know what G80 is?

(take with grain of salt that I know very little about GPU's)

Well, breaking G80 down by ALU's, it has 128 1D, which is "like" 32 of the old 4D kind. But they are double pumped so it is more like 64.

So lets say ATI is going to do a Xenos style chip as they have said. 96 4D ALU's would seem to provide them with a nice performance margin. Nvidia though would have presumably more efficiency to close the gap, and the direct comparison is only valid if R600 is clocked at 675 or more (since the Nvidia Alu's are 675 double pumped).

However Xenos is a small chip (~230m) with 48 alu's, so it seems like they would have lots of room for this.

They'd need at LEAST 32 TMU's for the throughput to compete. Hell, it seems to me the throughput is much more important than the shader power in determining how fast these chips are. It seems unlikely G80 is really stressing it's massive shader power with todays games. Yet it is much faster which must be due to the throughput. I'd like to see 64 full blown TMU's.

Then I'd like to see a 800 mhz clock. This might be unlikely though, it seems these big chips are taking a clock step backwards judging by G80. But who knows, ATI's design may have different capabilities.

[Chalnoth]

Well, I'd say the question will come down to nVidia's decision to go with fewer higher-clocked ALU's instead of more lower-clocked ALU's. I don't think that memory bandwidth will be a huge issue. It may rob or add a few percent here and there, but won't make or break the architecture. I don't think there's going to be a huge difference in capabilities, though it would surprise me if ATI also went with a scalar architecture.

[hoom]

Uhm, Rangers you start at G80 is equivalent to 64 4D ALUs at 675mhz which is fine.

But then you start talking about 96 4D ALUs at 800mhz as being competition?! Thats NV going 'thats not a knife, this is a knife' & ATI whipping out an SSBN.

A 96 ALU R600 should only need to hit something like 450mhz to be competitive.
If its 64 ALUs it needs to be 675mhz.

*all assuming same IPC per 4D ALU which we know isn't actually true

[INKster]

Another R600 rumour, and it's not from the Inq (i think...):

http://www.vr-zone.com/?i=4293

[R300King!]

Sounds like a power beast to me. I just hope it's performance is equal to it's power consumption.

[Rangers]

Originally Posted by arrrse

Uhm, Rangers you start at G80 is equivalent to 64 4D ALUs at 675mhz which is fine.

But then you start talking about 96 4D ALUs at 800mhz as being competition?! Thats NV going 'thats not a knife, this is a knife' & ATI whipping out an SSBN.

A 96 ALU R600 should only need to hit something like 450mhz to be competitive.
If its 64 ALUs it needs to be 675mhz.

*all assuming same IPC per 4D ALU which we know isn't actually true

You're just judging by shader power though. Which isn't, far from, the only factor here. Texture capabilities will also be key, which historically ATI might be deficient in.

Not too mention, the scalar ALU's are supposed to be more efficient right? So what we're talking about, the R600 having 50% more raw shader capability, Nvidia might make a chunk of that deficit back on efficiency, is what I'm presuming. And if ATI's chip isn't at least 675mhz, a hefty target, they'll make some more back there (all this pretending that the architectures are ALU-comparable, which of course they aren't). And by the time R600 comes out, it'll probably be dealing with a G80 refresh to boot.

Xenos seems to give good indication they ought to be able to get at least 96 ALU's in there to me, though. Or even R580.

[Razor1]

Originally Posted by Rangers

You're just judging by shader power though. Which isn't, far from, the only factor here. Texture capabilities will also be key, which historically ATI might be deficient in.

Not too mention, the scalar ALU's are supposed to be more efficient right? So what we're talking about, the R600 having 50% more raw shader capability, Nvidia might make a chunk of that deficit back on efficiency, is what I'm presuming. And if ATI's chip isn't at least 675mhz, a hefty target, they'll make some more back there (all this pretending that the architectures are ALU-comparable, which of course they aren't). And by the time R600 comes out, it'll probably be dealing with a G80 refresh to boot.

Xenos seems to give good indication they ought to be able to get at least 96 ALU's in there to me, though. Or even R580.

Sounds reasonable, but ATi will have to increase thier branching performance of the Xenos (batch size of 64), which would mean cutting down the size of thier SIMD, which will increase control silicon, to what amount I don't know, but in any case the chip will end up larger to some degree then Xenos if using the same amount of 48 ALU's, then have to factor in all the extra's, Dx10 functionality, AVIVO, etc. I don't think they will have an issue reaching the desired clock speed, they should be able to hit 600+, power might be a different story. But even with 96 shader array's they shouldn't have any problems going to 600, even if it was on .09, and we are pretty much certain its on .08 but teh .08 process won't yield much more to the clocks then .09, IMOH I think it will come down to how much power is going to be needed to drive it.

[Pete]

Do the rumors about the longer-than-G80GTX-PCB, high # of PCB layers, and high power draw support a 512-bit external memory bus (and so lots of RAM chips), or just lots of power draw (necessitating lots of power-massaging circuitry) from a power-hungry die?

B/c it seems to me that the external bus width would be key to determining the rest of the chip. It would seem to lead to 32 ROPs, at least 32 TMUs, and probably way over 64 shader "cores," considering both R580 and Xenos.

I'm skeptical ATI will have separate clock domains, and also skeptical that they'll put out a 64-shader core flying at well over 650MHz (I'm thinking RAM clocks, so close to 1GHz). So it seems to me that, barring G80-style double-clocked ALUs, R600'll just be brutally wide.

/clueless guessing

[Jawed]

Razor, I don't think anyone round here knows much about clocks on 80nm or how similar the 80nm node is to 90nm (especially as there are different grades at each node optimised for power or raw speed).

It's interesting that G80's shader-ALU clock, ~1350MHz, running on 90nm is the sort of thing that would never have been predicted before the rumours started. It isn't a minor thing NVidia has done with the 90nm process.

I'm not saying that R600 will run at similar rates - I'm merely using it as an example of something that's radically different from what we're used to.

Put another way, it seems fairly fruitless trying to argue configuration (branching granularity, etc.) based on clocks. If we'd known G80 was ~1.2GHz, back at the beginning of the year, would that have gotten us any closer to knowing the rest of the architecture?

Jawed

[Razor1]

That is true, I wouldn't be suprised if ATi has been looking into this too, something like fast 14, but here is the problem, ATi would have to take a large step away from thier current gen's to do something like what nV did with thier shader processors and start custom building libraries, I don't think ATi is taking that big of a step at least not yet anyways. This is the only way to go in the future though, nV might have opened a can of worms, where AMD can really give ATi an advantage.

Well if we need indication of .80 why did ATi go with strained silicon for thier latest notebook gpu. Strained silicon is expensive, last I heard 2 times the cost of regular silicon, and added to this SOI is also around 2 times the cost of regular silicon. Granted we are talking about a next gen product, but still, it all depends if ATi has taken an approach of hand building thier libraries and also if they went with simpiliar ALU's. If one is missing they won't be going for extreme high clocks and conservative power usage.

Pete I'm skeptical about the different clocks on ATi products aswell, they might be doing it though, after seeing what nV has done, I'm sure its crossed thier mind, but they probably won't be able to get great results with it yet, starting off slow would be thier best bet, but then again, look at the r520, and r580, those were some amazing chips and big leap in tech from ATi's side, nV took smaller steps once the nV 40 was out well, the g80 is a different monster altogether lol.

[Jawed]

Originally Posted by Razor1

That is true, I wouldn't be suprised if ATi has been looking into this too, something like fast 14, but here is the problem, ATi would have to take a large step away from thier current gen's to do something like what nV did with thier shader processors and start custom building libraries, I don't think ATi is taking that big of a step at least not yet anyways. This is the only way to go in the future though, nV might have opened a can of worms, where AMD can really give ATi an advantage.

Well, we've been wondering about fast14 for years now I think, which sorta tells us exactly nothing

What's weird is this assumption that "ATI can't possibly do anything to match NVidia". There's a wodge of stuff, conceptually, inside G80 that ATI did first, some of it years ago. NVidia could only compete this year by strapping two G71s together, G71 is that far behind on IQ and raw performance.

Well if we need indication of .80 why did ATi go with strained silicon for thier latest notebook gpu. Strained silicon is expensive, last I heard 2 times the cost of regular silicon, and added to this SOI is also around 2 times the cost of regular silicon. Granted we are talking about a next gen product, but still, it all depends if ATi has taken an approach of hand building thier libraries and also if they went with simpiliar ALU's. If one is missing they won't be going for extreme high clocks and conservative power usage.

I thought SS was for power consumption, which is obviously important to the mobile sector. ATI might have trialled SS on 90nm first? At some point ATI's 80nm GPUs will use SS? etc.

Jawed

[Chalnoth]

Well, the thing that really amazes me is just how big of a rabbit nVidia pulled out of its hat this time around. I really don't think that anybody was expecting the G80 to be this, at least not before around a month ago.

Now, if ATI was also in the dark, I don't know whether this will help or hurt them. For example, ATI could have deduced higher performance in today's games by projecting G7x-style logic density, but at a sacrifice in DX10 performance. But since it appears that nVidia went the other way entirely, well, we'll have to see. It'll be interesting, to say the least.

Personally I think that ATI's problems are more long-term in nature, with respect to priorities that are sure to change over time due to the merger.

[Shtal]

Originally Posted by Rangers

So I was thinking, what kind of specs does R600 need to beat G80.

I would says it might be this:

80nm
64 Shader pipelines (Vec4+Scalar)
32 TMU's
32 ROPs
128 Shader Operations per Cycle
650MHz Core
512GFLOPs for the shaders
512-bit 1024MB 2.0GHz GDDR4 Memory
128.0 GB/sec Bandwidth (at 1000MHz x2)

[Shtal]

What ATI actually need is to come to senses with R600 in order to show off in comparison with R580 X1950XTX.
R580 currently have 16 pipelines ratio 3:1 makes 48 pixel shaders.
R600 should be 64 pipelines ratio 2:1 makes 128 pixel shaders.
R580 currently have 16 ROP's
R600 should be 32 ROP's
R580 currently have 16 TMU's
R600 should be 32 TMU's
R580 currently have 32 x 8 crossbar on 256bit wide memory
R600 should be 64 x 8 corssbar on 512bit wide memory
R580 currently have 650MHz core clock
R600 should be at least 700MHz core clock (But that might not happend because chip is to hot)

All this comparison:
But unify shaders could have any combinations pixel/vertex geometry shaders is any way by the request. But I want to see in comparison with G80 who is better.

If this could truly happened it might put a lead over G80 about 20-25% MAX unless ATI have something better.
By the time this might happened I could be convince Nvidia will have back up plan.

[INKster]

Originally Posted by Shtal

I would says it might be this:

80nm
64 Shader pipelines (Vec4+Scalar)
32 TMU's
32 ROPs
128 Shader Operations per Cycle
650MHz Core
512GFLOPs for the shaders
512-bit 1024MB 2.0GHz GDDR4 Memory
128.0 GB/sec Bandwidth (at 1000MHz x2)

There are three things in there that i don't find credible for R600:

- 32 ROP's.
Is it really necessary to have more than 24 at the moment ?

- 512 bit external memory bus + 2.0 GHz effective GDDR4.
256bit + 2.8 GHz GDDR4 sounds like a more reasonable proposition to me.

- 650 MHz core.
Why does R600 need to have the same clockspeed as R580 ? G80 is at 575 MHz vs 650 MHz for the G71 and it didn't hurt them a bit. Personally, i find the raw core "MHz" spec as little more than a dying marketing trend.

[Dave Baumann]

Originally Posted by INKster

- 32 ROP's.
Is it really necessary to have more than 24 at the moment ?

Somewhat arbitary number isn't it? I assume, though, that number isn't wholly arbitary as its from 8800, but for what reason is that the ideal? I can certainly see why it would make sense for G80, but does that have to be the case for every graphics card?

[Shtal]

Originally Posted by INKster

There are three things in there that i don't find credible for R600:
- 32 ROP's.
Is it really necessary to have more than 24 at the moment ?.

It's all about I have something that you don't. It may not be necessary at the moment, but to show, we are late with the chip but we are not catching up with G80 but instead we are ahead.

Originally Posted by INKster

T- 512 bit external memory bus + 2.0 GHz effective GDDR4.
256bit + 2.8 GHz GDDR4 sounds like a more reasonable proposition to me.

It's all about I have something that you don't. You are Nvidia at 384bit but we are at 512bit. It maybe stupid but it could happened.

Originally Posted by INKster

There are three things in there that i don't find credible for R600:
- 650 MHz core.
Why does R600 need to have the same clockspeed as R580 ? G80 is at 575 MHz vs 650 MHz for the G71 and it didn't hurt them a bit. Personally, i find the raw core "MHz" spec as little more than a dying marketing trend.

It's all about marketing to show to consumers we have higher clock speed.
It may not be necessary at 650MHz.

[INKster]

Originally Posted by Dave Baumann

Somewhat arbitary number isn't it? I assume, though, that number isn't wholly arbitary as its from 8800, but for what reason is that the ideal? I can certainly see why it would make sense for G80, but does that have to be the case for every graphics card?

I've based my skepticism on the somewhat simplistic "doubling" of features relative to R580 that was stated.

R580 was faster than R520, but the same 16 ROP's didn't seem to hurt them, just like on Nvidia's high-end GF6/7.

As for new methods of AA, etc, they can in fact raise the stakes, but what if R600 has indeed 32 ROP's, but with each of them carrying no major changes from R5xx ?
Brute force from ATI ? It happened with R4xx, and the result was a lost opportunity to keep the momentum and gain further technology leadership compared to NV4x (seen as having better shading hardware, but also some downgrading on texture filtering quality, for instance).


Bah, what do i know ? You are the one who should have been giving us something to keep this thread alive and kicking.

[silent_guy]

Originally Posted by Pete

/clueless guessing

Speculating about what they are doing is pretty much useless, but it's clear what they should be doing:

• create something that's either so much faster than G80 that every alpha-gamer has to have it
• ... or create something that has the same or better !/$.

Preferably the latter... or both.

From a pure technical point of view, R580+ was better than G71 for pretty much all parameters in absolute terms.
But financially, it always had to play catch up because of its 350/192 die size disadvantage, which allowed Nvidia to either undercut ATI for the same performance or overpower them at the same price.

R580 was a sign of either an incompetent marketing department too insecure to cut features and demanding everything under the sun OR a weak marketing department unable to stand up against the desire of engineering to implement all the cool tricks, even if those add little or no pricing power. It's also an indication of engineering paying too much attention to ! instead of !/$ (and !/W.)

For the R600 and (especially!) its lower derivatives to be a success for ATI, they must have had the singular vision to drop the focus on pure performance alone and start caring about !/$ two or more years ago. Given their existing inefficient architecture, that means rethinking most if not all the blocks from scratch. Possible but IMHO unlikely.
If they didn't, they may well win the absolute performance crown (for now), but they'll keep losing ground in the mid-end segments, which is where the real money is made.

Edit: I guess what I'm saying is: none of the lists above mention silicon efficiency, even though that (and crappy execution) has been the biggest liability of ATI during the last few years.

[Dave Baumann]

Originally Posted by INKster

As for new methods of AA, etc, they can in fact raise the stakes, but what if R600 has indeed 32 ROP's, but with each of them carrying no major changes from R5xx ?

What if?

Here's an analogy - given the performances, it strikes me that a single G80 texture filter unit has some fairly similar properties to a G71 filter unit in relation to the samples per cycle. However, given the types of workloads now being seen, especially with HDR becoming more widely used and the bandwidth available to make it even more so, it appears to have made sense to NVIDIA to double them up per pixel in order to effectively get single cycle FP16 bilinear filtering (among other sampling traits).

Generally speaking I would say the "ideal" is more, more, more!!! But more to the point, the ideal is what makes sense for the design of the individual unit and the properties of the rest of the ecosystem of the processor.

[Shtal]

I agree with silent_guy.

But we all have to see if ATI will do better with R600 vs. R580

Since R600 is based on R500 Xones processor. It would be easer for ATI to make R600 more officiant then R580.

But I also agree what Dave Baumann is saying. Their is such a time frame what had occurred

[Dave Baumann]

Originally Posted by silent_guy

R580 was a sign of either an incompetent marketing department too insecure to cut features and demanding everything under the sun OR a weak marketing department unable to stand up against the desire of engineering to implement all the cool tricks, even if those add little or no pricing power.

You appear to say that relative to G71, however G71 was both released both after R580 and wouldn't have been known of in terms of properties when design started. Given the die size differences between R520 and R580 I don't think anyone would have refused a 3x math power increase.