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MSI NX7800GTX-VT2D256E (GeForce 7800 GTX)
By Vincent Chang
Category : Graphics
Published by Vijay Anand on Wednesday, 13th July, 2005
Rating : 4.5 out of 5 stars  

NVIDIA's Multiple Clocks

While it has been barely available for a month, the latest generation graphics card from NVIDIA, the GeForce 7800 GTX, has set the pulses of hardware enthusiasts racing with its impressive performance. You would think that despite its availability in retail, not that many people would be playing with it given its considerable price tag. Yet even within such a short period of time, hardware enthusiasts have already uncovered an unexpected aspect of this exciting new card. Namely, they discovered that the GPU frequency increased by around 40MHz whenever they started a 3D application. This subtle boost could only be observed through real-time monitoring of the GPU frequency.

It wasn't too long before someone in the community confronted NVIDIA about this. And the cat is now out of the bag. NVIDIA's Chief Scientist David Kirk has confirmed that there are multiple internal clocks that operate at different frequencies dynamically, depending on the load. While NVIDIA has not yet revealed the full details, the short version of the story is that the chipmaker has incorporated some power-saving techniques acquired from its experience with mobile parts in the design of the GeForce 7800 GTX. We are already well aware of this fact, but what no one realized is that they used this same clock-gating technique to increase frequencies in certain parts of the GPU. Essentially, there is no single clock speed for the GeForce 7800 GTX, as the internal clocks frequencies for different portions of the GPU scale up or down according to the demands on the card.

This previously unknown feature seems to be a trump card that NVIDIA has been unwilling to divulge until this surprise discovery. NVIDIA has promised to work with others in order to clarify the different frequencies and how that affects overclocking. With this information made known, so what does the 430MHz clock speed refer to when entering a 3D API? Well, it's simply a base/primary clock speed that the GPU operates in 3D mode. With this dynamic clock ramping in load situations, NVIDIA is actually giving users a speed boost, albeit without really made known in black and white. Meanwhile, there are questions about the extent of the vendors' knowledge of this hidden feature. After all, what does it really mean when vendors advertise their products as operating at a certain frequency when it has been revealed that the card naturally ramps up to such frequencies during 3D applications? Are they reflecting to this in the adverts? There is certainly potential for marketing mischief here and we've already identified some products that do play around this 'loophole'.

Putting aside such questions for now, we have already seen a pre-overclocked GeForce 7800 GTX from Leadtek and other vendors have introduced their own extreme versions of the GeForce 7800 GTX that offer higher frequencies. Today in our labs, we take a look at a GeForce 7800 GTX from MSI that also features vendor endorsed overclocking. As some of you may be aware, MSI has its own Dynamic Overclocking Technology (D.O.T), a software based utility that allows users to increase the frequencies by fixed intervals. We shall see how useful is that feature later but now, let's take a look at the card and its specifications:

Presenting MSI's version of the GeForce 7800 GTX.

MSI NX7800GTX-VT2D256E Technical Specifications
Graphics Engine
  • NVIDIA GeForce 7800 GTX GPU
    • Stock 2D GPU clock = 275MHz
    • Stock 3D GPU clock = 430MHz
  • NVIDIA CineFX 4.0 Shading Engine
    • Vertex Shaders
      • Support for DX 9.0 Vertex Shader 3.0
      • Displacement Mapping
      • Vertex Frequency Stream Divider (Geometry Instancing)
      • Infinite length vertex programs (supported in hardware)
    • Pixel Shaders
      • Support for DX 9.0 Pixel Shader 3.0
      • Full pixel branching support
      • Multiple Render Targets (MRTs)
      • Infinite length pixel programs (supported in hardware)
    • Texturing Engine Features
      • Accelerated textures access
      • Up to 16 textures per rendering pass
      • Support  for 16-bit and 32-bit floating point formats
      • Support for sRGB texture format for gamma textures
      • DirectX and S3TC texture compression
    • Full 128-bit FP Precision Graphics Pipeline
      • Native support for 32 / 64 / 128 bits per pixel rendering modes
  • 64-Bit Texture Filtering and Blending
  • NVIDIA UltraShadow II Technology (accelerates shadow  computations)
  • NVIDIA SLI Technology
  • NVIDIA Intellisample 4.0 Technology
    • 16x Anisotropic Filtering
    • Adaptive Texture Filtering
    • Gamma-adjusted Rotated Grid Antialiasing
    • Transparent multisampling and supersampling modes
    • Fast antialiasing and compression performance
    • Loss-less Color, Texture and Z-Data Compression algorithms (in real time)
    • Fast Z-clear
    • Support for normal map compression
  • NVIDIA PureVideo Technology
    • Dedicated programmable on-chip video processor
    • MPEG-2 video encode and decode
    • High Definition MPEG-2 and WMV9 hardware decode acceleration (up to 1080i)
    • Post Processing Features
      • Spatial-Temporal De-Interlacing (adaptive)
      • NTSC 3:2 Pulldown / Bad Edit correction
      • PAL 2:2 Pulldown correction
    • High quality 4x5 video scaling and filtering
    • Microsoft Video Mixing Renderer (VMR)
    • Integrated HDTV output (with HDCP support)
  • Composited Desktop Hardware Engine (for Windows Longhorn)
  • Advanced Video and Display Functionality
    • Dual 400MHz RAMDACs that support resolutions of 2048x1536@85Hz
    • Dual DVO ports for interfacing external TMDS transmitters and external TV/HDTV encoder
    • nView Multi-display Technology
  • NVIDIA Digital Vibrance Control (DVC) 3.0
  • Designed for PCI Express x16
  • Advanced thermal monitoring and thermal management
Graphics Memory
  • 256-bit memory interface
  • 256MB Graphics DDR3 SDRAM
  • Default clock rate of 600MHz (effective speed of 1200MHz DDR)
  • 38.4GB/sec Peak Memory Bandwidth
Display Capabilities
  • Dual 400MHz RAMDACs that support resolutions of 2048x1536@85Hz
  • Integrated dual TMDS transmitters (DVI 1.0 compliant and HDCP ready)
  • 1x mini-DIN connector (for Video-out)
  • 2x DVI-I connector (for Digital Flat Panel displays, compatible with analog displays with converter)
Drivers & Software
  • Driver support for Microsoft Windows 9x/ME/2000/XP/XP MCE/XP Pro x64, Linux and Macintosh OS (including OS X)
  • MSI Utilties (Live Update, GoodMEM, Lockbox, WMIinfo, SecureDoc)
  • MSI D.O.T. software
  • E-Color 3Deep
  • Norton Internet Security 2005
  • ThinSoft BeTwin
  • Media Ring Dialer
  • The Chronicles of Riddick: Escape from Butcher Bay
Other Information
  • PCI Express x16 slot required
  • Adjacent expansion slot to be kept free preferably
  • Dedidcated 6-pin PCIe Molex power connector required (not shared or split)
  • Power supply rated for 350W or higher receommended by NVIDIA (500W PSU for SLI setup)

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