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Specifications, Features and Peculiarities of NVIDIA GeForce 6800/6800 Ultra
NVIDIA’s last-generation graphics processors based around the NV30/NV35 architecture differed from ATI’s R300/R350 chips in higher flexibility, but the advantage in functionality of pixel processors led to a pretty slow shaders execution. This remains a sore spot of the CineFX/CineFX 2.0 architecture and GeForce FX chips in their competition with RADEON 9xxx graphics processors.
When developing the next-generation processor, NVIDIA couldn’t help relying on the previous experience. Of course, the company couldn’t stand a situation when solutions from its main rival were faster in nearly every price sector, in spite of NVIDIA’s formal technological superiority. That’s why besides further functionality enhancements and the introduced support of version 3.0 pixel shaders, they tried to give a performance boost to the NV40 and to enforce the weak sides of the CineFX architecture.
Here are the basic characteristics of the NVIDIA GeForce 6800 Ultra GPU in comparison with top-end graphics processors of the previous generation (NVIDIA GeForce FX 5950 Ultra and ATI RADEON 9800 XT).
NVIDIA GeForce 6800 Ultra
NVIDIA GeForce FX 5950 Ultra
ATI RADEON 9800 XT
Process technology
0.13 micron
0.13 micron
0.15 micron
Transistor Count
220 million
125 million
110 million
GPU clock-speed
400MHz
475MHz
412MHz
Memory controller
256 bit DDR/GDDR2/GDDR3
256 bit DDR SDRAM
256 bit DDR SDRAM
Memory clock-speed
1100 (550) MHz
950 (475 DDR) MHz
730 (365 DDR) MHz
Peak theoretical memory bandwidth
35.2GB/s
28.3GB/s
21.8GB/s
Maximum memory size
512MB?
256MB
256MB
AGP interface
AGP 3.0 4x/8x
AGP 3.0 4x/8x
AGP 3.0 4x/8x
Pixel processors, Pixel Shaders
Pixel shader version
3.0
2.x
2.0
Max number of pixels per clock
16
4
8
Max number of Z-values per clock
32
8
8
Number of TMUs
16
8
8
Static loops and branching
yes
no
no
Dynamic loops and branching
yes
no
no
Max number of textures per shader
16
16
16
Max number of texture instructions
n/a
1024
32
Max number of arithmetic instructions
n/a
1024
64 (+64)
Max number of instructions per shader
n/a
1024
96 (+64)
Registers
n/a
2 color registers, 512 (1024) constant registers, 8 texture coordinates registers, 16 TMU identification registers, 16 (32) temporary registers, 4 resulting color registers, 1 resulting Z register
2 color registers, 32 constant registers, 8 texture coordinates registers, 16 TMU identification registers, 12 temporary registers, 4 resulting color registers, 1 resulting Z register
Technologies aimed at higher memory bandwidth efficiency
Hidden Surfaces Removal (HSR)
yes
yes
yes
Frame-buffer, z-buffer, texture compression
yes
yes
yes
Fast Z-clear
yes
yes
yes
The list of parameters and features is impressive: this is a new-generation solution from any point of view. The pixel pipeline can output up to 16 pixels per clock cycle; there are 6 vertex processors – any competitor should beware of that power. The CineFX 3.0 architecture supports shaders version 3.0, a new full-screen anti-aliasing method, an improved anisotropic filtering algorithm, Ultra Shadow II technology for faster processing of shadows in next-generation games like Doom III. High-Precision Dynamic-Range technology allows building scenes with a high dynamic lighting coefficient.
Now let’s take a closer look at the basic characteristics of the NVIDIA NV40.
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