Architecture

There was a great deal of talk about why architectural decisions were made, but we will concern ourselves more with what exists rather than why this path was chosen. Every architecture will have its advantages and disadvantages, but understanding what lies beneath is a necessary part of the equation for developers to create efficient code for any architecture.

The first thing of note is NVIDIA's confirmation that 3dcenter.de did a very good job of wading through the patents that cover the NV3x architecture. We will be going into the block diagram of the shader/texture core in this description, but we won't be able to take quite as technical a look at the architecture as 3dcenter. Right now, we are more interested in bringing you the scoop on how the NV36 gets its speed.

For our architecture coverage, we will jump right into the block diagram of the Shader/Texture core on NV35:

As we can see from this diagram, the architecture is very complex. The shader/texture core works by operating on "quads" at a time (in a SIMD manner). These quads enter the pipeline via the gatekeeper which handles managing which ones need to go through the pipe next. This includes quads that have come back for a second pass through the shader.

What happens in the center of this pipeline is dependent upon the shader code running or the texturing operations being done on the current set of quads. There are a certain few restrictions on what can be going on in here that go beyond simply the precision of the data. For instance, NV35 has a max of 32 registers (less if higher precision is used), the core texture unit is able to put (at most) two textures on a quad every clock cycle, the shader and combiners cannot all read the same register at the same time, along with limits on the number of triangles and quads that can be in flight at a time. These things have made it necessary for developers to pay more attention to what they are doing with their code than just writing code that produces the desired mathematic result. Of course, NVIDIA is going to try to make this less of a task through their compiler technology (which we will get to in a second).

Let us examine why the 5700 Ultra is able to pull out the performance increases we will be exploring shortly. Looking in the combiner stage of the block diagram, we can see that we are able to either have two combiners per clock or complete two math operations per clock. This was the same as NV31, with a very important exception: pre-NV35 architectures implement the combiner in fx12 (12 bit integer), NV35, NV36, and NV38 all have combiners that operate in full fp32 precision mode. This allows two more floating point operations to be done per clock cycle and is a very large factor in the increase in performance we have seen when we step up from NV30 to NV35 and from NV31 to NV36. In the end, the 5700 Ultra is a reflection of the performance delta between NV30 and NV38 for the midrange cards.

If you want to take a deeper look at this technology, the previously mentioned 3dcenter article is a good place to start. From here, we will touch on NVIDIA's Unified Compiler technology and explain how NVIDIA plans on making code run as efficiently as possible on their hardware with less hand optimization.

The GeForce FX 5700 Ultra Compilation Integration
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  • Anonymous User - Friday, October 24, 2003 - link

    #57, don't comment on something you literally have no clue about. I make $60,000 a year and I live alone and really have no expenses to speak of, so I have plenty of money to spend hardware. I'm just finally savvy and am not one of those blind dolts who doesn't research his hardware and makes impulse purchases. I would have thought your high school teachers would have taught that to you last year.

    #59, I'm questioning the point of buying a $500 video card, period. More to the point though, I'm questioning people's over-analyization (hum, not a word I guess, you get the point though) of IQ in games, ESPECIALLY fps games where constant movement makes it almost impossible to notice the IQ differences you are seeing between NVIDIA and ATI cards with the latest drivers right now. Even more to the point, you need a high quality monitor IN ADDITION to that high-end video card to make the purchase worthwhile. When all is said and done, you could be spending $700 on just your monitor + video, and easily as high as $1000. Unless you play games 24/7 and are unemployed, you need to rethink your video card purchases.

    And what planet have you been on? AnandTech has written like 50 reviews the last two months, the majority of them 10+ page in depth articles on the latest hardware. Heck, AT is more than likely making money hand over fist. What do you know, except that the video fanatics with no credentials to speak of are claiming AnandTech has "gone down hill". LMAO, right!
  • Anonymous User - Thursday, October 23, 2003 - link

    Well I do not see how the review data supports his conclusions. And I also question the point of a review without any IQ testing but on a lighter not.

    You notice how NVIDIA drivers are now called FORCEWARE, thats because they force you to use the trilinear filtering they want, not what you want.
  • Anonymous User - Thursday, October 23, 2003 - link

    Given the detail reductions seen in the IQ analyses of the sites that have done them, the trend is becoming alarmingly clear - at least until the NV40 arrives, nvidia will not stop optmizations that reduce IQ in favor of speed. This is not a necessary result of the NV3X architecture, but a result of the quality of the competitor's product.

    The glaring lack of trilinear filtering in stages 2+ of all the FXes, and the inferior antialiasing quality gives one pause to even compare similar settings between the cards. The "good enough except to everyone else" FP16 modes continue, and real-time HDR lighting at FP16 or lower (FX12) shows obvious banding.
    Therefore, pronouncing a winner at a high price ($0.5K!) level without IQ analysis and basing the judgement on absolute frame rates (without intentionally decreasing the output quality of the competition to make the IQ directly comparable), is simply sad.

    Adieu anandtech, adieu!
  • Anonymous User - Thursday, October 23, 2003 - link

    #56 If youre dumb enough to spend 500 bucks on a video card and not care about IQ you're wasting your money

    And who said Anand has ever been reputable? They haven't been doing too well lately
  • Anonymous User - Thursday, October 23, 2003 - link

    i just saw a add for ati i guess #10 is wrong
  • Anonymous User - Thursday, October 23, 2003 - link

    #56 just because I can afford a $500 graphics card and still have money to afford everything else i want, doesn't mean I'm dumb. Maybe your "dumb" because you can't find a job that pays enough to have that luxury. Sux to be you....
  • Anonymous User - Thursday, October 23, 2003 - link

    Yikes, the video card fanboys, that aren't gamers in the first place, come full force with the criticisms. It doesn't get any more pathetic than a video fanatic that doesn't actually play any or even some of the games AnandTech used and still criticizes this review based on the total over-analysis that is Beyond3D. Though B3D does a through job and that should always be commended.

    And WTH, since when has [H] ever been reputable? Why do you think one of their editors left just recently? Kyle doesn't know jack about GPU, video architecture, or pretty much anything else besides what he picked up from his years of hands-on experience. Actually, this is a good thing in a way, because Kyle (and Brent, etc.) write reviews from a gamers' perspective. Still, the over-analysis of IQ is getting ridiculous. If you're dumb enough to spend $500 on a video card in the first place, you don't deserve IQ analysis.
  • Anonymous User - Thursday, October 23, 2003 - link

    #53/54: You each have a respective product that you enjoy, that doesn't give you free reign to lord minor victories for your preferred product over everyone else or whine that whenever a benchmark doesn't go your way that the competitor is cheating or lying or optimizing or buying a victory with ads.
    Overall, nVidia and ATI really don't care what you think about them, as long as they're making money off of you; I agree that both companies should be chastised for their optimizing of their drivers, but neither is doing anything that others haven't done in the past. You just haven't noticed it until someone started slinging mud in order to try and gain more market share (ATI). I really wish ATI had shut their pieholes about the "cheats", since now everyone and their mother is throwing accusations of cheating in their competitor's drivers as soon as the competition wins a benchmark or takes performance lead in an application.
    Utterly terrible. Fanboys, stop your engines, for you're just spinning your wheels. Go get a job with this newfound free time and buy more products from the companies you so vehemently support over the Intarweb 2.0, so that we may see better products sooner rather than later.
  • Anonymous User - Thursday, October 23, 2003 - link

    that comment just shows that you are just as childish as the rest of them #53
  • Anonymous User - Thursday, October 23, 2003 - link

    awww boo hooo

    ati fanboys getting pissed? criticizing every site that doesn't agree with you is not going to help your credibility you know.

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