6600GT PCI-E Specifications

Graphics Bus	PCI Express
Memory Interface	128-bit
Memory Bandwidth	16.0 GB/sec.
Fill Rate (texels/sec.)	4.0 billion
Vertices per Second	375 million
Memory Data Rate	1000 MHz
Pixels per Clock (peak)	8
RAMDACs	400 MHz
Core	NV43
Core Speed	500 MHz

6600GT Features

Revolutionary Superscalar Architecture
Delivers up to 8x the shading power of previous generation products for screaming gaming performance.

CineFX 3.0 Engine
Powers the next generation of cinematic realism. Full support for Microsoft® DirectX® 9.0 Shader Model 3.0 enables stunning and complex special effects. Next-generation shader architecture delivers faster and smoother gameplay.

NVIDIA PureVideo Technology
The combination of the GeForce 6 Series GPUs’ high-definition video processor and NVIDIA video decode software delivers unprecedented HD video, stunning picture clarity, smooth video, accurate color, and precise image scaling for all video content to turn your PC into a high-end home theater. Feature requires supported video software. Features may vary by product.

Adaptable Programmable Video Processor
PureVideo’s programmable technology adapts to new video encoding formats as they are developed to provide a future-proof video solution.

UltraShadow II Technology
Enhances the performance of bleeding-edge games, like id Software’s Doom III, that feature complex scenes with multiple light sources and objects. 2nd-generation technology delivers more than 4x the shadow processing power over the previous generation.

64-Bit Texture Filtering and Blending
Based on the OpenEXR technology from Industrial Light & Magic, NVIDIA’s 64-bit texture implementation sets new standards for image clarity and quality through floating point capabilities in shading, filtering, texturing, and blending.

Intellisample 3.0 Technology
The industry’s fastest antialiasing delivers ultra-realistic visuals, with no jagged edges, at lightning-fast speeds. Visual quality is taken to new heights through a new rotated grid sampling pattern.

Unified Driver Architecture (UDA)
Part of the NVIDIA Forceware unified software environment (USE). The NVIDIA UDA guarantees forward and backward compatibility with software drivers. Simplifies upgrading to a new NVIDIA product because all NVIDIA products work with the same driver software.

nView Multi-Display Technology
The nView hardware and software technology combination delivers maximum flexibility for multi-display options, and provides unprecedented end-user control of the desktop experience. NVIDIA GPUs are enabled to support multi-displays, but graphics cards vary. Please verify multi-display support in the graphics card before purchasing.

Digital Vibrance Control 3.0 Technology
Allows the user to adjust color controls digitally to compensate for the lighting conditions of their workspace, in order to achieve accurate, bright colors in all conditions.

NVIDIA SLI Technology
Dramatically scales performance by allowing two graphics cards to be run in parallel. (GeForce 6800 Ultra, 6800 GT, 6800 LE, 6800, and 6600 GT only)

PCI Express Certified
Designed to run perfectly with the next-generation PCI Express bus architecture. This new bus doubles the bandwidth of AGP 8X delivering over 4GB/s in both upstream and downstream data transfers. Only supported in some NVIDIA GPUs. Please check product details for bus information.

Microsoft® DirectX® 9.0 Optimizations and Support
Ensures the best performance and application compatibility for all DirectX 9 applications

High-Definition MPEG-2 Hardware Acceleration
Smoothly playback all MPEG-2 video with minimal CPU usage so the PC is free to do other work. Battery-life is extended when watching DVDs while running on battery. MPEG-2 is the standard format for DVDs, is accepted as a format for HD-DVD, and is also used for HD broadcast.

High-Quality Real-Time Video Recording
Get full digital video recording functionality without losing data. With NVIDIA PureVideo technology, high-quality recording preserves picture detail while also using minimal space to store videos on the hard drive.

WMV-HD Hardware Acceleration
Playback videos in Microsoft’s Windows Media Video High Definition (WMV-HD) format without skipping frames or losing video detail. Accepted by the HD-DVD consortium as a new HD format, WMV-HD is now part of Windows XP to make it easy for users to edit and save their favorite videos.

Advanced Spatial Temporal De-Interlacing
Smoothes video and DVD playback on progressive displays to deliver a crisp, clear picture that rivals high-end home theater systems.

Vibrant Color Temperature Correction
Color temperature correction makes actors’ faces appear natural, rather than washed out and pale, when playing videos on LCD and CRT displays.

High-Speed GDDR3 Memory Interface
Support for the world’s fastest GDDR3 memory delivers fluid frame rates for even the most advanced games and applications. (Supported in the GeForce Go 6800, GeForce 6800 Ultra, 6800 GT, 6800, and 6600 GT only)

Full-Speed 32-Bit Color Precision
Delivers increased image quality with no performance compromise.

OpenGL® 2.0 Optimizations and Support
Ensures the best performance and application compatibility for all OpenGL applications.

Dual 400MHz RAMDACs
Blazing-fast RAMDACs support dual QXGA displays with ultra-high, ergonomic refresh rates–up to 2048x1536 @ 85Hz.

Dual-Link DVI Support
Able to drive the industry’s largest and highest resolution flat-panel displays.

Microsoft® DirectX® 9.0 Shader Model 3.0 Support
Ensures top-notch compatibility and performance for all DirectX 9 applications, including Shader Model 3.0 titles.

Integrated HDTV Encoder
Provides world-class HDTV-out functionality up to and including 1920x1080i resolutions.

Wow that's a lot of features.  This information was taken directly from the nvidia webpage.