NVIDIA's GeForce 6800 Ultra - NV40 Debuts

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NVIDIA's GeForce 6800 Ultra - Page 2

The GeForce 6800 Ultra
NVIDIA's NV40 Debuts...

By, Marco Chiappetta
April 14, 2004

With the GeForce 6800 Ultra, NVIDIA is not only the first company to introduce GDDR3 equipped video cards and 16 pixel pipelines in a single chip, but they've expanded the feature set of their GPUs to fully support the relatively new Shader Model 3.0 as well.  The GeForce 6800 Ultra also has a new video engine built-into the chip,  a new anti-aliasing method, and a beefed up version of NVIDIA's proprietary UltraShadow technology...

New Feature Spotlight: GeForce 6800 Ultra
Wider is Better  |  Più largamente è migliore

CineFX 3.0 & Shader Model 3.0:

Shader Model 3.0, which will be available upon the release of DirectX 9.0c, basically builds upon Shader Model 2.0 by increasing the maximum number of Vertex and Pixel shader instructions that can be executed by the GPU, and by raising the minimum level of shader precision required to be compliant.  The GeForce 6 Series can process an infinite number of pixel and vertex shader instructions, which far exceeds the minimum specification of 65,536.  The GeForce 6 Series also has support for Displacement mapping, Vertex Texture Fetch, Pixel Shader Subroutines, Loops & Branches and Dynamic Flow control.  Support for these specifications make the NV40 act more like a general purpose CPU, giving it the ability to process instructions with more flexibility, which in-turn gives developers more freedom when programming complex shaders.



The NVIDIA GeForce 6 Series also has a new shader architecture that can double the number of operations executed per clock cycle.  Each of the NV40's pipelines is now equipped with a second shading unit (right).  Traditional shaders (left) generally have a single shading unit that can process up to 4 operations per pixel, per clock cycle.  By adding a second shading unit to each pipeline the NV40 architecture delivers a twofold increase in the number pixel operations that can be processed per clock cycle.  This "superscalar" architecture, as NVIDIA calls it, is capable of up to four instructions and eight operations per pixel, compared to just two instructions and four operations in traditional architectures.

UltraShadow II:

As games and their underlying game engines get more complex, and have to use multiple passes to render shadows from different light sources, the need to process these shadows efficiently and quickly gets increasingly more important.  With the NV3x architecture, NVIDIA introduced a proprietary technology called "UltraShadow" that helps render complex shadows relatively quickly, when compared to products without UltraShadow.  NVIDIA pointed to ID's upcoming game Doom 3 as one of the titles that benefit greatly from their UltraShadow technology.  Back in June '03 we spoke to NVIDIA about this technology, and asked how it gives them a performance advantage.  Basically, what UltraShadow does is cull shadows that fall outside of a defined depth bound - if a shadow falls outside of the boundary it is not rendered.  This saves processing time, and bandwidth, which ultimately increases performance.  With the GeForce 6800 Ultra, NVIDIA is introducing UltraShadow II, and extension of their technology which offers up tp 4x the performance of the NV35.

Intellisample 3.0 & Rotated Grid Anti-aliasing:

NVIDIA has also revamped their anti-aliasing engine with the GeForce 6 series.  Cards based on the NV3x used a four sub-pixel pattern that was sampled in a two-by-two grid for each pixel.  By slightly rotating the grid into somewhat of a diamond shape (similar to ATI's technique with the R3x0 architecture), the resulting pattern of the four sub-pixels samples four values for the horizontal and vertical sub-pixel positions. Using samples that are essentially closer to the original pixel results in more accurate colors at the polygon's edge.  The more accurate the colors, the less prominent jaggies will appear in any given frame, which gives the overall appearance of fewer jaggies in the scene.

NVIDIA HPDR (High Precision Dynamic Range):

The GeForce 6 Series is capable of Studio-Quality, HDR (High Dynamic Range) rendering that complies with the OpenEXR format developed by Industrial Light & Magic (ILM) of Lucasarts fame.  ILM developed the OpenEXR format in response to the demand for higher color fidelity in the visual effects industry.  In scenes with a very bright light source in conjunction with extremely dark shadows, there tends to be color banding in the dark portions of the scene where the eye can better perceive slight differences in color.  NVIDIA's HPDR technology, which is completely implemented in hardware, solves the problem of high dynamic-range rendering by providing 16-bit floating point formats for storage, blending, shading, texturing, and filtering during the light transport phase. It also allows for the use of the sRGB format in the tone mapping and color and gamma correction phases. For more details, and in-depth explanations as to how HDR rendering can affect an image, we strongly suggest checking out the examples on the OpenEXR website - as they say, a picture is worth a thousand words.

On-Chip Video Processor:

The NV40 also sports an on-chip programmable video processor designed to improve the quality and performance of video playback on the PC.  NVIDIA's on-chip video processor incorporates a high-quality adaptive de-interlacing engine, along with better filtering and scaling techniques, video de-blocking capabilities and an integrated TV-encoder.  The NV40's on-chip video processor is also a complete HDTV solution as well, with the ability to output HDTV streams in all of the popular formats (720P, 1080i, 480P, CGMS).  It also has PVR (Personal Video Recorder) functionality, with hardware audio / video synchronization, hardware MPEG 1 / 2 / 4 encoding and decoding, and WMV9 decode acceleration.

Eye Candy: NVIDIA's Demos
Showing Off the Features...


Sailing with NVIDIA, Dr. Timbury and the lovely Nalu...

Upon the introduction of a new architecture, NVIDIA always produces a few spectacular demos designed to highlight the product's key features and performance.  At a recent press event we got to see all three of the demos pictured above running live on the NV40, and can say these screen captures do not do them justice.  The Sailing demo especially looked much better live and in motion.  It seems like these shots were taken with an early build of the demo, as the one we were shown had the water splashing up on the sides of the ship as it crashed into the waves.  The Dr. Timbury demo, was also fairly impressive.  We weren't too fond of the "cartoon-like" look, but when the camera was positioned to show the NV40's HDR rendering at work, the light bloomed around, and reflected off his shiny head, in a very realistic fashion.  Then we have Nalu.  Nalu is the mermaid cousin, of Dusk & Dawn - the NV3x nymphs.  Nalu has evolved to have much more realistic looking skin, translucent shader effects for her "clothes" and fins, and her hair is comprised of 10,000 individually animated strands.  The overall effect was very realistic, especially when she spun and turned to show its movement.

The Drivers: Forceware v60.72
Without The Software, The Hardware is Useless



Color Correction

Clock Frequencies

Performance & Quality


Screen Adjustment


Display Timing


Tying all of the hardware's features to the operating system is NVIDIA's Forceware drive suite.  Release 60 of the Forceware drivers add support for the GeForce 6 series of products, as well as NVIDIA's PCI Express products based on the NV3x architecture.  Unified Compiler performance has been improved approximately 10% - 35%, an optimized PS3.0 complier has been added, and support for NV4x's video engine has been incorporated as well.  Release 60 also integrates all of the new features first introduced with the Forceware 55 release, like a built in pop-up blocker, application specific profiles and auto overclocking (on supported products).  We've already covered these new features in more detail in a previous article, so we don't spend too much time on them here.  But if you'd like to read up on them, head on over to this page.  Release 60 is designated as beta at the moment, and should be ready for public consumption at the end of May.

Anti-Aliasing Image Quality

Tags:  Nvidia, GeForce, Ultra, force, 680, ULT, BU, id

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