NVIDIA's 1.4 Billion Transistor GPU: GT200 Arrives as the GeForce GTX 280 & 260
by Anand Lal Shimpi & Derek Wilson on June 16, 2008 9:00 AM EST- Posted in
- GPUs
NVIDIA's Dirty Dealing with DX10.1 and How GT200 Doesn't Support it
I know many people were hoping to see DX10.1 implemented in GT200 hardware, but that is not the case. NVIDIA has opted to skip including some of the features of DX10.1 in this generation of their architecture. We are in a situation as with DX9 where SM2.0 hardware was able to do the same things as SM3.0 hardware albeit at reduced performance or efficiency. DX10.1 does not enable a new class of graphics quality or performance, but does enable more options to developers to simplify their code and it does enhance performance when coding certain effects and features.
It's useful to point out that, in spite of the fact that NVIDIA doesn't support DX10.1 and DX10 offers no caps bits, NVIDIA does enable developers to query their driver on support for a feature. This is how they can support multisample readback and any other DX10.1 feature that they chose to expose in this manner. Sure, part of the point of DX10 was to eliminate the need for developers to worry about varying capabilities, but that doesn't mean hardware vendors can't expose those features in other ways. Supporting DX10.1 is all or nothing, but enabling features beyond DX10 that happen to be part of DX10.1 is possible, and NVIDIA has done this for multisample readback and can do it for other things.
While we would love to see NVIDIA and AMD both adopt the same featureset, just as we wish AMD had picked up SM3.0 in R4xx hardware, we can understand the decision to exclude support for the features DX10.1 requires. NVIDIA is well within reason to decide that the ROI on implementing hardware for DX10.1 is not high enough to warrant it. That's all fine and good.
But then PR, marketing and developer relations get involved and what was a simple engineering decision gets turned into something ridiculous.
We know that both G80 and R600 both supported some of the DX10.1 featureset. Our goal at the least has been to determine which, if any, features were added to GT200. We would ideally like to know what DX10.1 specific features GT200 does and does not support, but we'll take what we can get. After asking our question, this is the response we got from NVIDIA Technical Marketing:
"We support Multisample readback, which is about the only dx10.1 feature (some) developers are interested in. If we say what we can't do, ATI will try to have developers do it, which can only harm pc gaming and frustrate gamers."
The policy decision that has lead us to run into this type of response at every turn is reprehensible. Aside from being blatantly untrue at any level, it leaves us to wonder why we find ourselves even having to respond to this sort of a statement. Let's start with why NVIDIA's official position holds no water and then we'll get on to the bit about what it could mean.
The statement multisample readback is the only thing some developers are interested in is untrue: cube map arrays come in quite handy for simplifying and accelerating multiple applications. Necessary? no, but useful? yes. Separate per-MRT blend modes could become useful as deferred shading continues to evolve, and part of what would be great about supporting these features is that they allow developers and researchers to experiment. I get that not many devs will get up in arms about int16 blends, but some DX10.1 features are interesting, and, more to the point, would be even more compelling if both AMD and NVIDIA supported them.
Next, the idea that developers in collusion with ATI would actively try to harm pc gaming and frustrate gamers is false (and wreaks of paranoia). Developers are interested in doing the fastest most efficient thing to get their desired result with as little trouble to themselves as possible. If a techique makes sense, they will either take it or leave it. The goal of a developer is to make the game as enjoyable as possible for as many gamers as possible, and enabling the same experience on both AMD and NVIDIA hardware is vital. Games won't come out with either one of the two major GPU vendors unable to run the game properly because it is bad for the game and bad for the developer.
Just like NVIDIA made an engineering decision about support for DX10.1 features, every game developer must weight the ROI of implementing a specific feature or using a certain technique. With NVIDIA not supporting DX10.1, doing anything DX10.1 becomes less attractive to a developer because they need to write a DX10 code path anyway. Unless a DX10.1 code path is trivial to implement, produces the same result as DX10, and provides some benefit on hardware supporting DX10.1 there is no way it will ever make it into games. Unless there is some sort of marketing deal in place with a publisher to unbalance things which is a fundamental problem with going beyond developer relations and tech support and designing marketing campaigns based on how many games dispaly a particular hardware vendors logo.
The idea that NVIDIA is going to somehow hide the capabilities of their hardware from AMD is also naive. The competition through the use of xrays, electron microscopes and other tools of reverse engineering are going to be the first to discover all the ins and outs of how a piece of silicon works once it hits the market. NIVIDA knows AMD will study GT200 because NVIDIA knows it would be foolish for them not to have an RV670 core on their own chopping block. AMD will know how best to program GT200 before developers do and independantly of any blanket list of features we happen to publish on launch day.
So who really suffers from NVIDIA's flawed policy of silence and deception? The first to feel it are the hardware enthusiasts who love learning about hardware. Next in line are the developers because they don't even know what features NVIDIA is capable of offering. Of course, there is AMD who won't be able to sell developers on support for features that could make their hardware perform better because NVIDIA hardware doesn't support it (even if it does). Finally there are the gamers who can and will never know what could have been if a developer had easy access to just one more tool.
So why would NVIDIA take this less than honorable path? The possibilities are endless, but we're happy to help with a few suggestions. It could just be as simple as preventing AMD from getting code into games that runs well on their hardware (as may have happened with Assassin's Creed). It could be that the features NVIDIA does support are incredibly subpar in performance: just because you can do something doesn't mean you can do it well and admitting support might make them look worse than denying it. It could be that the fundamental architecture is incapable of performing certain basic functions and that reengineering from the ground up would be required for DX10.1 support.
NVIDIA insists that if it reveals it's true feature set, AMD will buy off a bunch of developers with its vast hoards of cash to enable support for DX10.1 code NVIDIA can't run. Oh wait, I'm sorry, NVIDIA is worth twice as much as AMD who is billions in debt and struggling to keep up with its competitors on the CPU and GPU side. So we ask: who do you think is more likely to start buying off developers to the detriment of the industry?
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epobirs - Monday, June 16, 2008 - link
There is an important precedent that gives Nvidia good reason to not rush to a new smaller process level. Recall when ATI first became a serious player in gaming GPUs with the 9700. It was for its time a big chip pushing the limits of the process level, while Nvidia at the time was concentrating on bleeding edge technology. Nvidia's chips got stomped by ATI's in that generation, in large part because the ATI chip had far better optimization of its transistors.anartik - Monday, June 16, 2008 - link
We can agree the pricing sucks. But the point that seems to be missing is that Nvidia promised a 50% performance improvement and they delivered. The 280 delivers 45FPS vs 32FPS for the 9800GT in Assassins creed. Thats just shy of 50% (48FPS) which is a huge performance increase compared to what we have been getting the past couple years for a new card. Slap 2x280 on a card and it vaporizes the 9800 GX2 or any SLI/Xfire solution. The 9800 GX2 scales ~63% over the 9800GTX. So if you do that for a 280GX2 (or SLI) you get roughly 73 frames per second. Plus the new cards have more memory to deal with bandwidth and large textures vs the nuetered 512 on the 96/9800's and 8800GT... the reason I have held onto my 8800 GTX with 768mb. Granted I won't be rushing out and buying one tomorrow but the 280 is the fastest GPU and a x2 will be faster than any other x2 card. It's a little rediculous to think the single 280 sucks becuase it's not faster than multiple GPU's like the 9800 GX2 (although when memory counts it is).araczynski - Monday, June 16, 2008 - link
this is all they could spit out? all that noise and all those transistors and it gets its ass handed to it by the gx2 more often than not?talk about fizzle, perhaps at best it'll lower the price of the gx2 a bit.
not to mention no built in hdmi, good lord, they must've had two seperate teams working on the gtx and gx2 at the same time and just wanted to see what they could come up with separately.
Ananke - Monday, June 16, 2008 - link
I don't think many people at this forum tread understand that nVidia target is the supercomputer market. I was totally impressed from one post a month ago, where a software engineer managed to put and use 3 SLI system for magnetoresonance rendering. Nvidia and AMD /that's why they acquired ATI/ have already significant experience in multiprocessor and parallel calculation. nVidia is ahead though, since they have CUDA becoming more popular for complex calculation. A year ago Intel realized parallel processing from Sun is their biggest danger, now nVidia and Ati come too. Imagine, supercomputers build with thousands of G200 chips, and only some Intels used for mapping, instead of thousands of Xeons. nVidia thinks way more ahead just for the mere visual/gaming market. I am very very impressed, and very eager to see what ATI can do. Also, I hope Ati and Havoc will be able to offer competition to CUDA, or uniformity? Anyway, from a scientific point of view, recent developments in the graphic market make foundamental science more affordable than anytime before.Reflex - Monday, June 16, 2008 - link
Anand/Derek -I am not sure why you are comparing this chip to a Penryn or other general purpose CPU as the comparisons are meaningless. GPU's are designed very differently than CPU's, namely a high level descriptor language is used and the design is then created by a program, which is then hand tweaked by engineers. By contrast, a CPU may use a high level language, but the actual design is almost entirely done by hand, with large teams working on each sub component and literally years of tweaking. It takes Intel between five and ten years to bring a design to market, which is why there is such a push by them to keep adjusting the design and optimizing it to stretch its usefulness out as long as possible to maximize the initial investment. This simply does not happen with a GPU.
GPU's are designed to last 18-24 months as a competitive solution. nVidia and Ati cannot afford to spend even five years designing them. As a result the level of hand optimization is greatly reduced, and inefficiencies with transistors are tolerated. Typically they are produced on equipment that is already paid for by the previous, more optimized products, or contracted out to third parties(TSMC). Since the products are sold for a premium, the wasted die space is not very relevant. It is a diametrically opposed process to what you see with CPU development.
Despite how impressive it may seem to go on about 1.4 billion transisters, truthfully a modern CPU does more with far less than a modern GPU, and honestly neither nVidia nor Ati are in the same league as Intel and AMD, neither at the engineering level nor when comparing the products they put out. To an Intel engineer, this GPU is at least four times larger than it needs to be to get the performance you get out of it.
The maturation of the industry, either due to reaching a point where GPU's can do 90% of what anyone needs, or simply because power budgets get more restrictive, will come when the level of optimization required for a CPU is required for a GPU, and product cycles stretch out to 3-5 years. Then you will have a more direct comparison between the two, since the design parameters will be much more similiar.
I am not knocking nV here, btw, I'm simply calling into question why one would even compare a Penryn to a GPU, it makes no sense at all when they were designed from the ground up for different purposes, lifespans and with different transister budgets.
7Enigma - Tuesday, June 17, 2008 - link
I think what this shows is there a brute force way of doing something that while not necessarily pretty can get you to a goal. Yes compared to Intel's latest and greatest it is a grotesque abomination of wasted energy/transistors/die size, but the bottom line is it is pretty darn impressive from a CPU/GPU standpoint.I think many of us long for the days of more than 2 major competetors for each race (CPU/GPU). We've been stuck in a rut with ATI and Nvidia, AMD and Intel. Yes you have some niche products by other companies, and budget pieces being made by a host of has-beens, but really tier 1 stuff is just not being fought over by more than 2 companies.
What I want to see (complete dreamland here) is a start up from some very savvy disgruntled employees of say AMD/ATI, Intel, IBM, etc. (and don't forget possibly the most important segment, the marketing team) with some clout and a LOT of dough to say, "Screw this, we're going balls to the wall and throw the kitchen sink at the market."
I mean let's be honest here, what's another 100 watts or a billion transistors anymore? I can guarantee you every geek out there would shell out more money for a product that devestates the current competition. I don't care if it's not as frugal with the power, or as small, or as pretty, I want the speed man, gimme the speed!
Anand Lal Shimpi - Monday, June 16, 2008 - link
While I'd normally agree with you, GPUs have been getting pretty complex to design. Much of the shader multiprocessors in G80 and GT200 were designed by hand, and remember that G80 (the original predecessor to GT200) was in development for four years before its launch.The transistor comparison is a valid one, while Penryn is a very impressive design, it is so for different reasons than GT200. The size of GT200 also helps illustrate fundamental differences in approach to CPU vs. GPU design and really highlights why Intel is building Larrabee.
-A
crimson117 - Monday, June 16, 2008 - link
Because to non-engineers, they're two silicon computer chips, and 1.4 billion of anything is a lot!It also helps me to visually understand why this thing gets so hot, since it's got so much more surface area packed with transistors.
You're right that CPUs and GPUs are designed for different tasks and shouldn't be considered pure apples to apples, but then you go against your own advice and start saying how CPUs are so much more advanced, and how Intel engineers could do that in 1/4 the size of a chip. So which is it - should they be compared, or should they not be compared?
And the authors did mention how simple it could be for either company to slap the other type of chip right in with their usual type; make a Intel CPU with added GPU capabilities, or make a nVidia GPU with CPU capabilities. So there's another point where they recognize the differences but do try to illustrate the sameness.
So I'm not really sure your criticisms hold water.
Reflex - Monday, June 16, 2008 - link
You are looking for contradictions where there are none. A chip is a chip, but that does not mean that they are all designed with the same goals, budgets and time constraints. *IF* Intel devoted the resources to a GPU that they devote to a CPU, yes they could produce a product like this in a fraction of the transisters. That said, the product would take 5-10 years to design, would cost hundreds of millions of dollars to develop, and would need a lifespan of at least 5 years in the market to be worth the effort. Obviously this is not a reasonable approach in a market with such fast product turnover.My post was not an attempt to diss nV or this product, it was pointing out that the comparison of a GPU to a CPU is inane as they have completely different design constraints. You may as well compare a CPU to cache memory, or RAM or a sound processor. All have transisters, right?
It especially bothered me when they implied that nVidia has the transister budget to toss a general purpose CPU on the die. The fact is that they may have the transister budget, but they do not have the time or money available to do so, and the product would be obsolete before it ever hit the market as a result of such an attempt. It would be marrying two completely different design philosophies, and this is why the combined CPU/GPU products that are upcoming are not likely to be the strongest performers.
paydirt - Monday, June 16, 2008 - link
You all seem to be assuming that GPUs will only be used for games. If that's all you care about, then why do you whine when a GPU is made to perform well as a number cruncher (for science, for modeling/simulations)?It's the best single GPU gaming card.
It's the best widely (?) available GPU number cruncher.
For a whole system gaming GPU solution, it isn't the most cost effective.
If you're all into numbers, then why are you assigning emotions to it. It simply is what it is.