Gigabyte GeForce 6800 GT 256 MB review

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 Introducing the GeForce 6800 GTThe core itself is build upon a 0.13 Micron Process technology, which is fabricated at IBM. The 6800 indeed has a lot of transistors. I personally didn't count them but NVIDIA states that there are 222 Million transistors. Imagine all that on a 40mm x 40mm FlipChip GPU running roughly 350-400 MHz. And in case you are wondering yes... the transistor count is actually higher than a Pentium 4 Extreme Edition. Since we are on the topic of the core, there are 6 vertex units inside it. One of the biggest advantages of the Series 6 is of course the increased number of pixel pipelines. The more the faster, is the generic consensus.

Let me explain briefly what happens in the 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 from 8 towards 16 pipes can bring you a dramatic performance increase. I have to note here that these are not theoretical pipelines as rumored by some websites prior to the product announcements. They are scalable though, each pipe is available at any time in sets of 4. Where NV35 was stereotyped as 4x2/8x0 architecture, the NV40 is 16x1/32x0.

Architecture Characteristics of the GeForce 6 Series

  • Pixel pipelines: 16
  • Superscalar shader: Yes
  • Pixel shader operations/pixel: 8
  • Pixel shader operations/clock: 128
  • Pixel shader precision: 32 bits
  • Single texture pixels/clock: 16
  • Dual texture pixels/clock: 8
  • Adaptive Anisotropic Filtering: Yes
  • Z-stencil pixels/clock: 32

The silicon itself is of course PCI-Express ready yet the one we are talking about is running steady on AGP 8x. PCI-Express has double the bandwidth of AGP8x and another plus; it allows data to be sent in both directions.

Back in March at CeBIT, I was told by an NVIDIA representative that the GPU can actually handle AGP 16x internally at core level... now think about PCI-Express again. The 6800 Ultra is equipped with the latest available in affordable yet really fast GDD3 memory; on the 6800 Ultra it is running at 1.2 GHz (2x600 MHz) whereas today's product, the GT, is running at 1 GHz (2x500 MHz). BTW GDDR3 is designed in a way that its temperature is much cooler. It's likely we are going to see manufacturers making 6800 cards without ramsinks.

  • 222 Million transistors
  • 350 MHz Core Clock
  • 500 MHz memory Clock
  • 256-bit GDDR3 memory

To tidy things up a bit I've made a little overview

  • 16 pipeline GPU architecture (12 on 6800 Non Ultra).
  • Up-to 8x more shading performance compared to the previous generation
  • CineFX 3.0 engine - Yes indeed... DirectX Shaders model 3.0 for really nice visual effects
  • On Chip Video processor.
  • DDR3 memory on a 256-bit Memory interface @ 1 GHz
  • UltraShadow II technology - Doom III; need I say more ? Very well then...3x to 4x faster than NV35 !
  • High Precision Dynamic Range (HPDR) technology - we'll discuss this later in the article
  • 128-studio precision through the entire pipeline - 32-bit Color precision; this time with nice performance.
  • IntelliSample 3.0 Technology - 16x Anisotropic Filtering & Rotating Grid Anti Aliasing
  • Full MPEG encoding and decoding at GPU level !
  • Advanced Adaptive De-Interlacing
  • Video Scaling and Filtering - HQ filtering techniques including HDTV resolutions
  • Integrated TV Encoder - TV-output up-to 1028x768 resolutions
  • OpenGL 1.5 Optimizations and support
  • DVC 3.0 (Digital Vibrance Control)
  • Dual 400 MHz RAMDACs which support QXGA displays up-to 2048x1536 @ 85 Hz
  • Dual DVI

 

Specs GeForce 6600 GeForce 6600 GT GeForce 6800 GeForce 6800 GT GeForce 6800 Ultra
Codename NV43 NV43 NV40 NV40GT NV40U
Transistors ? ? 222 million
Process, GPU maker 110nm 110nm 130nm, IBM
Core clock 300 MHz 500 MHz Up to 400 MHz 350MHz 400-450 MHz
Memory 128MB DDR1 128MB GDDR3 128MB DDR1 256MB GDDR3 256MB GDDR3
Memory bus 128-bit 256-bit
Memory clock Up to manufacturer 2x500 MHz 2 x 550MHz 2 x 500MHz 2 x 600MHz
PCB P212 P212 P2?? P210 P210
Pipelines 8 8 12 16 16
FP operations FP16, FP32
DirectX DirectX 9.0c
Pixel shaders PS 3.0
Vertex shaders VS 3.0
OpenGL 1.5+ (2.0)
Price $150 $229 $299 $399 $499
Availability Sep/Oct 2004 Sep/Oct 2004 May/June 2004

 

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