HIS and Sapphire Radeon HD 4850 Face Off

Tuesday, October 07, 2008 - by Robert Maloney in Video

With the recent run of newer and more affordable graphics cards from ATI, it's almost easy to forget that there's already a sub-$200 frame-rate cruncher called the Radeon HD 4850.  Based on the same RV770 chip as the more powerful, yet more expensive HD 4870, the HD 4850 ships with the same 800 stream processors, 40 texture units, and 16 ROPs that have made these cards such hot items.  The main area where they differ, other than clock speeds, is in regard to memory.  While the HD 4870 ships with high-end GDDR5 memory chips, the HD 4850 finds itself loaded with 512 MB of more mainstream GDDR3.

A major caveat with the Radeon HD 4850 that has arisen, however, is the excessive heat that gets produced by the RV770 GPU.  It seemed the single slot reference cooling solution had a tough time handling the heat output of the RV770.  With heat being a concern, and manufacturers having more time to tinker with their cards, we weren't surprised to find out that two of ATI's major partners, HIS and Sapphire, had two new cards waiting in the wings, each with their own ramped up clock speeds but with some superior cooling thrown in as well.  Before we get down to comparing these two head-to-head, let's take a quick look at the basic specifications of the Radeon HD 4850. 


AMD ATI Radeon HD 4800 Series
Specifications and Features

  • 956 million transistors on 55nm fabrication process
  • PCI Express 2.0 x16 bus interface
  • 256-bit GDDR3 memory interface

  • Microsoft DirectX 10.1 support

    • Shader Model 4.1
    • 32-bit floating point texture filtering
    • Indexed cube map arrays
    • Independent blend modes per render target
    • Pixel coverage sample masking
    • Read/write multi-sample surfaces with shaders
    • Gather4 texture fetching

  • Unified Superscalar Shader Architecture

    • 800 stream processing units

      • Dynamic load balancing and resource allocation for vertex, geometry, and pixel shaders
      • Common instruction set and texture unit access supported for all types of shaders
      • Dedicated branch execution units and texture address processors
    • 128-bit floating point precision for all operations
    • Command processor for reduced CPU overhead
    • Shader instruction and constant caches
    • Up to 160 texture fetches per clock cycle
    • Up to 128 textures per pixel
    • Fully associative multi-level texture cache design
    • DXTC and 3Dc+ texture compression
    • High resolution texture support (up to 8192 x 8192)
    • Fully associative texture Z/stencil cache designs
    • Double-sided hierarchical Z/stencil buffer
    • Early Z test, Re-Z, Z Range optimization, and Fast Z Clear
    • Lossless Z & stencil compression (up to 128:1)
    • Lossless color compression (up to 8:1)
    • 8 render targets (MRTs) with anti-aliasing support
    • Physics processing support

  • Dynamic Geometry Acceleration

    • High performance vertex cache
    • Programmable tessellation unit
    • Accelerated geometry shader path for geometry amplification
    • Memory read/write cache for improved stream output performance

  • Anti-aliasing features

    • Multi-sample anti-aliasing (2, 4 or 8 samples per pixel)
    • Up to 24x Custom Filter Anti-Aliasing (CFAA) for improved quality
    • Adaptive super-sampling and multi-sampling
    • Gamma correct
    • Super AA (ATI CrossFireX configurations only)
    • All anti-aliasing features compatible with HDR rendering

  • Texture filtering features

    • 2x/4x/8x/16x high quality adaptive anisotropic filtering modes (up to 128 taps per pixel)
    • 128-bit floating point HDR texture filtering
    • sRGB filtering (gamma/degamma)
    • Percentage Closer Filtering (PCF)
    • Depth & stencil texture (DST) format support
    • Shared exponent HDR (RGBE 9:9:9:5) texture format support
  • OpenGL 2.0
  • ATI PowerPlay
  • Advanced power management technology for optimal performance and power savings
  • Performance-on-Demand
    • Constantly monitors GPU activity, dynamically adjusting clocks and voltage based on user scenario

    • Clock and memory speed throttling

    • Voltage switching

    • Dynamic clock gating

    • Central thermal management – on-chip sensor monitors GPU temperature and triggers thermal actions as required

  • ATI Avivo HD Video and Display Platform

    • 2nd generation Unified Video Decoder (UVD 2)

      • Enabling hardware decode acceleration of H.264, VC-1 and MPEG-2
      • Dual stream playback (or Picture-in-picture)

    • Hardware MPEG-1, and DivX video decode acceleration

      • Motion compensation and IDCT

    • ATI Avivo Video Post Processor

      • New enhanced DVD upconversion to HD new!
      • New automatic and dynamic contrast adjustment new!
      • Color space conversion
      • Chroma subsampling format conversion
      • Horizontal and vertical scaling
      • Gamma correction
      • Advanced vector adaptive per-pixel de-interlacing
      • De-blocking and noise reduction filtering
      • Detail enhancement
      • Inverse telecine (2:2 and 3:2 pull-down correction)
      • Bad edit correction
      • Full score in HQV (SD) and HQV (HD) video quality benchmarks

    • Two independent display controllers

      • Drive two displays simultaneously with independent resolutions, refresh rates, color controls and video overlays for each display
      • Full 30-bit display processing
      • Programmable piecewise linear gamma correction, color correction, and color space conversion
      • Spatial/temporal dithering provides 30-bit color quality on 24-bit and 18-bit displays
      • High quality pre- and post-scaling engines, with underscan support for all display outputs
      • Content-adaptive de-flicker filtering for interlaced displays
      • Fast, glitch-free mode switching
      • Hardware cursor

    • Two integrated DVI display outputs

      • Primary supports 18-, 24-, and 30-bit digital displays at all resolutions up to 1920x1200 (single-link DVI) or 2560x1600 (dual-link DVI)
      • Secondary supports 18-, 24-, and 30-bit digital displays at all resolutions up to 1920x1200 (single-link DVI only)
      • Each includes a dual-link HDCP encoder with on-chip key storage for high resolution playback of protected content4

    • Two integrated 400MHz 30-bit RAMDACs

      • Each supports analog displays connected by VGA at all resolutions up to 2048x1536

    • DisplayPort output support

      • Supports 24- and 30-bit displays at all resolutions up to 2560x1600

    • HDMI output support

      • Supports all display resolutions up to 1920x1080
      • Integrated HD audio controller with up to 2 channel 48 kHz stereo or multi-channel (7.1) AC3 enabling a plug-and-play cable-less audio solution

    • Integrated AMD Xilleon HDTV encoder

      • Provides high quality analog TV output (component/S-video/composite)
      • Supports SDTV and HDTV resolutions
      • Underscan and overscan compensation
      • MPEG-2, MPEG-4, DivX, WMV9, VC-1, and H.264/AVC encoding and transcoding
      • Seamless integration of pixel shaders with video in real time
      • VGA mode support on all display output

    • ATI CrossFireX Multi-GPU Technology

      • Scale up rendering performance and image quality with two GPUs
      • Integrated compositing engine
      • High performance dual channel bridge interconnect

     

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    While the specs above give you a detailed technical overview of what makes the HD 4850 tick, it doesn't cover all of the nuances that you might be looking for.  However, since we've already extensively covered the technology behind not only the HD 4850, but the HD 4870 as well, we won't rehash that information here again. If you want to learn more about the technologies employed by ATI, please take a look at the following previous articles, which cover them in detal:

    Once up to speed, we'll take a closer look at our two entries in today's HD 4850 Face-off: the HIS Radeon HD 4850 IceQ4 TurboX and Sapphire's Toxic Radeon HD 4850.

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    Tags: Radeon, Sapphire, HD, App

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