ATI Radeon HD 4890: The RV790 Unveiled - HotHardware

ATI Radeon HD 4890: The RV790 Unveiled

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As anyone remotely in tune with the tech sector can attest, the rivalry in the PC graphics card market between AMD / ATI and NVIDIA is as intense as ever. It used to be that one of the two companies would release a new product, only to have the other release a competing offering a few weeks, or maybe a few months later. But even in these gloomy economic times, AMD and NVIDIA continue to fight on and today both graphics giants are releasing new graphics cards aimed squarely at one another. Not a few weeks apart, but simultaneously on the very same day. Don't believe us? See here for our NVIDIA GeForce GTX 275 coverage.

AMD is rolling out the ATI Radeon HD 4890 today, technically a new graphics card, but one that borrows heavily from the previous generation. The Radeon HD 4890 is based on an updated variant of the popular RV770 GPU which powers Radeon HD 4850 and 4870 cards, dubbed the RV790. We've got some technical details regarding the RV790 GPU below and have more particulars regarding the actual cards and performance on the pages ahead. Read on to see what AMD has in store with the brand new Radeon HD 4890...


Asus ATI Radeon HD 4890 (RV790)

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/GDDR5 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 support
  • 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)3
      • 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 2048x15363
    • DisplayPort output support

      • Supports 24- and 30-bit displays at all resolutions up to 2560x16003
    • HDMI output support

      • Supports all display resolutions up to 1920x10803
      • 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 outputs
    • 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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    AMD RV790 / Radeon HD 4890 Details

    The new Radeon HD 4890 is technically based on a new GPU design, which was formerly codenamed RV790, but fundamentally it is very similar to the RV770-based Radeon HD 4870. The two GPUs share the same feature set, same compliment of shader processors (800), texture units, and ROP configurations. Because we've covered the architectural details of the RV770 in a previous article, we won't do the same again here. If you'd like a little refresher, however, we'd recommended checking out our Radeon HD 4800 series launch article from last year. All of the details necessary to understand what's going on under the Radeon HD 4890's hood are in that article.

    Although the features are technically very similar, the RV790 does differ from the RV770 in a number of ways. Some may be tempted to say the RV790 is simply an overclocked RV770, but that is not the case. The RV790 at the heart of the Radeon HD 4890 is a new chip that is comprised of more transistors than the RV770 (959M vs. 956M). The additional transistors are dedicated to updates made to the core to support higher clock speeds. According to AMD, the entire chip was re-timed and power distribution on the chip was altered. In addition, a decap ring--or ring of decoupling capacitors--was implemented around the chip to reduce signal noise. The changes to the core and the addition of the decap ring result in an increase in die and packaging size, but the end result is a GPU that can run at much higher clock speeds than the RV770.

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    I knew this was coming. I myself am even though an ATI GPU user not excited about this card itself. I am excited about the prices that will result from it's release. Both AMD/Nvidia will most likely start another price war at least to some extent, bringing prices for performance down further.

    Also as per there previous actions in the GPU battle before the 3800 line they released a stand alone top end of the preceding ATI high end card (the XT2950 I think it was). Then a two or three months later they dropped the 3870/50 models. So this may be a pre cursor to some sense.

    I am not saying I have any inside info on it. Thats just what I remember them doing a couple years back. I also find it funny this card is a 55nm card, just like there last one, but rumour had it they were going to 45nm for there next GPU set.

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    article:
    While the power consumption numbers put the 4890 and 4870 in a similar league, we can say the 4890 runs much cooler than the 4870. Our Asus Radeon HD 4890 cards idled at under 50'C and peaked in the mid 80's under load. But where we noticed the biggest difference was when we removed the cards from the test system. After testing, the Radeon HD 4890 felt very warm to the touch when removing it from the test rig, but the Radeon HD 4870 was so much hotter, it was almost too hot to handle without giving it a few minutes to cool down. Not exactly a scientific data point, but something we wanted to mention nonetheless.
    I can attest to how hot the 4870s get. This is a huge plus for the 4890.

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    The pace of new hardware coming out is a bit overwhelming but thrilling to.Im nowhere near some of you guys ability on obtaining some of this but one way or another Im setting my goals to at least getting an i7 and a Asus board this summer and just go from there!Hopefully with a stimulas check Im suppose to get from my disability will get me started.Maybe the i7/920 and the new Asus p6 with ddr3.Ive got 2 cases one Im redoing and one fairly new one to put something in and cant wait!ITs like going to a toy store everyday when I sign on to HH and read up on all the new tech/TOYS.Hopefully this year will better than last.

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