G70 is NVIDIA internal codename for the GeForce 7800 GTX. The 7800 GTX is the new flagship, the fastest available. And I know that many of you are wondering if will there be an AGP version. To be honest, at this time and moment NVIDIA has no plans for it. That doesn't mean it'll never happen though as they can use the well known bridge chip (High Speed Interconnect) and make it AGP compatible. Face it, AGP is becoming history whether we like it or not.
Let's dig a little deeper into the chip. As you know the number of transistors in the actual silicon gives us a nice idea about performance. Intel's new Pentium 4 6xx series for example has 169 million transistors. The GeForce 6800 already had 222 million transistors. The GeForce 7800 GTX silicon has an astounding 302 million transistors count, crazy huh? All that is being manufactured on a 0.11 micron fabrication process.
| Specs |
GeForce 6600 |
GeForce 6600 GT |
GeForce 6800 |
GeForce 6800 GT |
GeForce 6800 Ultra |
GeForce 7800 GT |
GeForce 7800 GTX |
| Codename |
NV43 |
NV43 |
NV40 |
NV40GT |
NV40U |
G71 |
G70 |
| Transistors |
? |
? |
222 million |
302 million |
302 million |
| Process, GPU maker |
110nm |
110nm |
130nm, IBM |
110nm |
110nm |
| Core clock |
300 MHz |
500 MHz |
Up to 400 MHz |
350MHz |
400MHz |
400 MHz |
430 MHz |
| Memory |
128MB DDR1 |
128MB GDDR3 |
128MB DDR1 |
256MB GDDR3 |
| Memory bus |
128-bit |
256-bit |
| Memory clock |
Up to manufacturer |
2x500 MHz |
2 x 325MHz |
2 x 500MHz |
2 x 600MHz |
2 x 500MHz |
2 x 600MHz |
| PCB |
P212 |
P212 |
P2?? |
P210 |
P210 |
- |
| Pipelines |
8 |
8 |
12 |
16 |
16 |
20 |
24 |
| FP operations |
FP16, FP32 |
| DirectX |
DirectX 9.0c |
| Pixel shaders |
Pixel Shaders 3.0 |
| Vertex shaders |
Vertex Shaders 3.0 |
| OpenGL |
1.5+ (2.0) |
2.0 |
| Price |
$150 |
$229 |
$299 |
$399 |
$499 |
$449 |
$599 |
| Availability |
Now |
| What is a shader ? |
| What do we need to render a three dimensional object; 2D on your monitor? We start off by building some sort of structure that has a surface, that surface is being built from triangles and why triangles? They are quick to calculate. How's each triangle being processed? Each triangle has to be transformed according to its relative position and orientation to the viewer. Each of the three vertices the triangle is made up of is transformed to its proper view space position. The next step is to light the triangle by taking the transformed vertices and applying a lighting calculation for every light defined in the scene. At last the triangle needs to be projected to the screen in order to rasterize it. During rasterization the triangle will be shaded and textured.
Graphic processors like the GeForce series are able to perform a certain amount of these tasks. The first generation was able to draw shaded and textured triangles in hardware. The CPU still had the burden to feed the graphics processor with transformed and lit vertices, triangle gradients for shading and texturing, etc. Integrating the triangle setup into the chip logic was the next step and finally even transformation and lighting (TnL) was possible in hardware, reducing the CPU load considerably (GeForce 256). The big disadvantage was that a game programmer had no direct (i.e. program driven) control over transformation, lighting and pixel rendering because all the calculation models were fixed on the chip. And now we finally get to the stage where we can explain Shaders. Vertex and Pixel shaders allow developers to code customized transformation and lighting calculations as well as pixel coloring functionality. Each shader is basically nothing more than a relatively small program executed on the graphics processor to control either vertex or pixel processing. |
So what are the major advantages over the Series 6 6800 Ultra? Well, feature wise we are looking pretty much at the same technology. There are a few differences though, which we'll get into later. Overall the 7800 GTX is mostly about increased efficiency and higher performance over the previous generation product.
Normally we see little steps though, yet with 24 pipes, 8 vertex units, a huge transistor count combined with some nice internal hardware optimizations, the boost in performance is noticeable.
- 256-bit GeForce 7800 GTX (430MHz clock)
- 302 Million transistors
- 8 Vertex Shading Units
- 24 Pixel pipelines
- 256MB 256-bit 1.6ns (8x32) GDDR3 Memory (630MHz clock - 1.26 GHz effective)
- PCI Express x16 Compatibility (PCI Express Compliant)
- Integrated NVIDIA TV Encoder (HDTV, S-Video, Composite,)
- Integrated NVIDIA VIVO (S-Video, Composite,)
- Dual DVI-I Connectors
- 38.4 GB per second memory bandwidth
- NVIDIA PureVideo Technology
- DVD + HDTV Decode assist up to 1920x1080p resolution
- Integrated Dual 400MHz RAMDACs
- 1 Dual Link TMDS DVI Connector
- 1 Single Link TMDS DVI Connector
- NVIDIA Digital Vibrance Control (DVC) 3.0
- Support for Microsoft Video Mixer Renderer (VMR)
- Advanced adaptive de-interlacing
The first reaction when you look at the architecture of the G70 chip is that it is a prolonged 6800 core. Not entirely true, NVIDIA made some stern changes inside where all that magic happens. According to NVIDIA the internal pipelines were from top to bottom redesigned to make sure there was lower and thus better latency.
This increased performance is for each and any clock cycle. Not only that though, according to NVIDIA the vertex units have been rebuilt to increase geometric performance, a new texture engine accelerates texture processing and there are a number of other things that guarantee better performance. All in all the focus on this design was to increase its shader supremacy as this is where the future of gaming must be found.
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