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Introduction
Not long ago, NVIDIA told us to expect a 6-months long product cycle. But it took them almost a year to launch a completely new GPU to replace the GeForce 6800 Ultra.
Christened the GeForce 7800 GTX, this GPU originally bore the code-name G70. However, this does not mean that the GeForce 7800 GTX is a completely new GPU design. This GPU is actually an improved version of the NV40 core. But unlike the past NVIDIA upgrades of the NV3x core which basically feature only a bump in the clock speed, the G70 is much more than that.
NVIDIA has even claimed that the G70 has been reworked from the ground up. While GeForce 7800 GTX has retained most of the features found in NV40, like SLI (Scalable Link Interface) expansion and Microsoft® DirectX® 9.0 Shader Model 3.0 support, that's basically where the similarity ends.
Architecturally, the GeForce 7800 GTX comes with 8 vertex units and 24 pixel pipelines, 33% and 50% more than its predecessor. Both core and memory clock speeds have also been increased slightly to 430MHz and 600MHz (1200MHz DDR) respectively.
Here are some short comparison charts of the GeForce 7800 GTX versus the GeForce 6800 series.
| GeForce 7800 GTX |
GeForce 6800 Ultra |
GeForce 6800 GT |
|
| Architecture |
G70 |
NV40U |
NV40U |
| Manufacturing Process |
0.11 Micron |
0.13 Micron |
0.13 Micron |
| Transistor Count |
302 Million |
222 Million |
222 Million |
| DirectX Support |
9.0c |
9.0c |
9.0c |
| Interface |
PCIe |
AGP/PCIe |
AGP/PCIe |
| Vertex Pipelines |
8 |
6 |
6 |
| Vertex
Shader Version |
3.0 |
3.0 |
3.0 |
| Pixel
/ Texture Pipelines |
24 x 1 |
16 x 1 |
16 x 1 |
| Pixel
Shader Version |
3.0 |
3.0 |
3.0 |
| Core
Speed |
430 MHz |
400 MHz |
350 MHz |
| Fill
Rate |
10320 MTexels/s |
6400 MTexels/s |
5600 MTexels/s |
| Memory
Bus Width |
256-bits |
256-bits |
256-bits |
| Memory Type |
GDDR3 |
GDDR3 |
GDDR3 |
| Memory
Speed |
600 MHz |
550 MHz |
500 MHz |
| Memory Bandwidth |
38.40 GB/s |
35.20 GB/s |
32.00 GB/s |
As you can see from the table above, the G70 enjoys a die-shrink to just 0.11 micron. Even with a 15% smaller die process, the G70 die is still larger than the NV40's die, thanks to the extra 80 million transistors NVIDIA crammed into the new core.
The GeForce 7800 GTX Features
Here's a list of the new GeForce 7800 GTX's features :
- Microsoft® DirectX® 9.0 Shader Model 3.0 Support
- NVIDIA® CineFX™ 4.0 Engine
- NVIDIA® SLI™ Technology
- NVIDIA® Intellisample™ 4.0 Technology
- 64-Bit Floating Point Texture Filtering and Blending
- NVIDIA® PureVideo™ Technology
- Adaptable Programmable Video Processor
- High-Definition MPEG-2 and WMV Hardware Acceleration
- Advanced Motion Adaptive De-Interlacing
- Video Scaling and Filtering
- Video Color Correction
- Integrated HDTV Encoder
- 256-Bit Memory Interface
- NVIDIA® UltraShadow™ II Technology
- 128-Bit Studio-Precision Computation
- OpenGL® 2.0 Optimizations and Support
- NVIDIA® nView® Multi-Display Technology
Other than NVIDIA's PureVideo, which was not available in the previous top-of-the-line GeForce 6800-series of cards, most of the GeForce 7800 GTX's features are nothing new.
