"With
the NVIDIA 6800 Ultra you have the most powerful, most technologically
advanced, and most flexible 3D graphics card that you can get. The 6800
Ultra brings the best in new technology like Shader Model 3.0, along with
more than enough performance head-room to satisfy the most avid gamers.
No matter what you might be hearing, the 6800 Ultra is the best, and I'll
tell you why." -
Keith Rochford, Chief Engineer, EVGA.com Corp.
With the launch of a new generation of graphics cards, there is always the
accompanying debate as to whose design is better. That endless debate recently
received new life with the launch of the NVIDIA 6800 series and the ATI X800
series of cards. Almost predictibly, a number of review sites began posting
different benchmark results, that in many cases showed the new offering from
ATI in a much better light. However, many of you who are old hands with video
card launches already know that these intial reports can be somewhat misleading.
Quite often, new technology is tested with programs that were designed against
the last generation of graphics cards, and don't really show the whole story.
With that being said, let's take a look at both NVIDIA's and ATI's latest offerings
and see what's really going on under the hood.
NVIDIA 6800 Ultra vs. ATI X800 XT Technology Comparison |
|
NVIDIA 6800 Ultra |
ATI X800 XT |
Vertex Units |
6 |
6 |
Shader Units |
16-32 |
16 |
Texture Units |
16 |
16 |
Shader Model 3.0 Support |
Yes |
No |
64-bit FP Frame Buffer Blending |
Yes |
No |
64-bit FP Texture Filtering |
Yes |
No |
On-Chip Video Processor |
Yes |
No |
From this we can see right away that the NVIDIA offering contains a significant
number of technological improvements as compared the the ATI offering. The most
important of those differences is in the support for Shader Model 3.0 - this
is the very thing that will allow life-like games and 3D simulations to come
alive with complex shading routines that were not even close to possible under
the previous versions.
The importance of Shader Model 3.0 cannot be overstated, it allows for incredibly
powerful graphics routines to be written that generate an evolutionary leap
in 3D realism. So important is Shader Model 3.0 that even ATI has publically
admitted it's benefits:
"Pixel Shader 3.0 allows longer shader programs,
which in turn implies more realistic materials and better quality lighting."
"...it makes sense to believe
it'll take less time before games make use of it. New games
that enter development after the launch of Pixel Shader 3.0
hardware will probably hit the shelves six to 12 months later."
-Richard Huddy, Director Developer Relations, ATI
Custom PC Magazine, May 2004
|
So what is it that makes Shader Model 3.0 so much better? Is it a small change
or is it one that will really make an impact? Take a look at the chart below
to see just how dramatic a change it really is:
Pixel Shader Feature |
Shader 3.0 |
Shader
2.0 |
Description |
Shader Length |
65535+ |
96 |
Allows more complex shading, lighting, and procedural materials |
Dynamic Branching |
Yes |
No |
Saves performance by skipping complex shading on irrelevant pixels |
Shader anti-aliasing |
Built-in derivative instructions |
Not
supported |
Developers can calculate the screen space derivatives of any funciton, allowing them to adjust shading frequencies or over-sampling to eliminate artifacts |
Back-face register |
Yes |
No |
Allows two-sided lighting in a single pass |
Interpolated color format |
32-bit floating point minimum |
8-bit
integer minimum |
Higher range and precision color allows high-dynamic range lighting at the vertex level |
Multiple render targets |
Required |
Optional |
Allows advanced lighting algorithms to save filtering and vertex work - thus more lights for minimal cost |
Fog and specular |
Custom fp16-fp32 shader program |
8-bit
fixed function minimum |
Shader Model 3.0 gives developers full and precise control over specular and fog computations, previously fixed function |
Texture coordinate count |
10 |
8 |
More per-pixel inputs allows more realistic rendering, especially for skin |
Excerpted from "Shader Model 3.0 - No Limits",
by D. Sim Dietrich Jr., Nvidia, Microsoft
Windows Hardware and Driver Central
In short, Shader
Model 3.0 is a huge step forward in terms of ease of use, performance, and
shader complexity; which in turn allows developers improved performance and
simplified development opportunities.
Upcoming (and Present) Shader 3.0 Titles
- FarCry
- Lord of the Rings, Battle For Middle-earth
- STALKER: Shadow of Chernobyl
- Vampire: Bloodlines
- Tiger Woods 2005
- Madden 2005
- Grafan
- Painkiller
|
-Keith Rochford, Chief Engineer, EVGA.com Corp. |