XFX GeForce 7800 GS Extreme Edition

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Inside the graphics processor

Allow me to talk swiftly about the graphics core of the GeForce 7800 GS.

Copyright 2005 - Guru3D.comThe Codename: We always love them. The 7800 GS series (and at one point I really do expect an PCI-Express version) has been developed under the G70 family of GPU's, G70 who we all know and love as it's called the GeForce 7800 GTX.

NVIDIA_BR02.DEV_00F5.1 = "NVIDIA GeForce 7800 GS"

The core: So in fact the 7800 GS is simply a G70 core with disabled vertex and pixel units. The core has 302 million transistors and is based on a .11 micron fabrication process.

Since we are on the topic of the graphics core, inside it there are precisely six vertex units active, one more than I initially expected. The number of pixel pipelines are identical to the 6800 GT and Ultra model, there are sixteen of them. Let me enlighten briefly what happens in the pixel pipeline for you to understand its importance. Each pixel that is rendered on your screen goes through a pipe where it'll receive its complex color/effect etc. Each time that pixel is altered it'll pass through the pixel pipeline, one pass is one clock cycle. You can imagine going 16 pipes is nothing to be ashamed about. The Series 7 7800 GT and GTX actually have 24 of them. Last but not least, for the freaks, the 7800 GS AGP has eight ROPs. ROP is short for Raster Operation and a portion of a pipeline, responsible for AA, Blending and Z-Buffer compression. Simply stated a ROP is basically the output engine of a pixel shader pipeline. The pipeline is scalable, each pipe is available at any time in sets of 4, which we call quads.

Small note here: you can not enable disabled pipelines or vertex units with Rivatuner ! It's simply not possible.

The clockworks: the standard AGP version of the 7800 GS will be clocked at 375 MHz for the graphics processor and 2x600 on the memory. Memory is gDDR3 with a 38.4 GB/sec theoretical bandwidth. That's great memory bandwidth for sixteen pipeline product. XFX however as explained on the previous page already will clock the card much faster at default for you.

Specs GeForce 6600 GeForce 6600 GT GeForce 6800 GeForce 6800 GS GeForce 6800 GT GeForce 6800 Ultra GeForce 7800 GS GeForce 7800 GT GeForce 7800 GTX
Codename NV43 NV43 NV42 NV42 NV40GT NV40U G70 G70 G70
Transistors ? ? 222 million 302 million 302 million 302 million
Process, GPU maker 110nm 110nm 130nm 110nm pcx
130nm agp		 130nm
110nm 110nm 110nmCore clock 300 MHz 500 MHz Up to 400 MHz 425 PCX
350 AGP 350MHz 400MHz 375 MHz 400 MHz 430 MHzMemory 128MB DDR1 128MB GDDR3 128MB DDR1 128/256MB gDDR3 256MB GDDR3Memory bus 128-bit 256-bitMemory clock Up to manufacturer 2x500 MHz 2 x 325MHz 2x
500MHz 2 x 500MHz 2 x 600MHz 2 x 500MHz 2 x 600MHzPCB P212 P212 P2?? P210 P210 -Pipelines 8 8 12 16 16 16 20 24FP operations FP16, FP32DirectX DirectX 9.0cPixel shaders Pixel Shaders 3.0Vertex shaders Vertex Shaders 3.0OpenGL 1.5+ (2.0) 2.0Availability Now

NVIDIA reference specification
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.

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