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ATI Radeon HD 4870 X2 - AMD Back On Top
Date: Aug 12, 2008
Author: Marco Chiappetta
Intro, Specifications and Related Info

AMD hasn't exactly kept the product we're going to be showing you here today a secret. Once NVIDIA launched the GeForce GTX 200 series, and AMD had a look at what the cards could do first hand, AMD's marketing machine was tuned up and revved to its redline expunging the features and benefits of their upcoming GPU. Then, when the initial products in the Radeon HD 4800 series launched, AMD's plan became quite clear.

The Radeon HD 4800 series didn't overwhelm NVIDIA's GTX 200 series with raw performance. In fact, the GeForce GTX 280 and 9800 GX2 were more powerful than the Radeon HD 4870. The Radeon HD 4800 series cards, however, were still excellent cards and they were offered at extremely competitive prices, which put significant pressure on NVIDA. At the time of their launch, the Radeon HD 4850 and Radeon HD 4870 were both less expensive and more powerful than the GeForce 9800 GTX and GeForce GTX 260, respectively.  Since then, NVIDIA has reacted with a quick round of price cuts.

While enthusiasts were contemplating the purchase of a new Radeon or GeForce, AMD then planted another seed and released some concrete details regarding the Radeon HD 4870 X2, as if to say, "Yeah, we've got you covered at the $300 price point and a new, ultra powerful behemoth is coming real soon too. Maybe you should hold onto your upgrade money for a bit?"

That behemoth is the Radeon HD 4870 X2. As its name suggests, the card features two RV770 GPUs running in tandem, for what is effectively a Radeon HD 4870 CrossFire configuration on a single PCB. Other than its pair of GPUs, however, the Radeon HD 4870 X2 has a few more differentiating factors we'll need to tell you about. Read on for the full scoop... 


ATI Radeon HD 4870 X2 Cards (Codename R700)

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


  • As the above list of specifications and features show, the new Radeon HD 4870 X2 has the exact same features as the Radeon HD 4870; it just has two GPUs.  Like the other members of the Radeon HD 4800 series, the Radeon HD 4870 X2 offers DX10.1 and Shader Model 4.1 support, the GPUs are manufactured on TSMC's 55nm process node, and both support ATI's CrossFireX multi-GPU technology.

    Because we've covered essentially all of the shared features of the Radeon HD 4800 and 3800 series cards before, we won't be going into them in depth again here.  However, we would recommend taking a look at a few recent articles to brush up on the tech if you're so inclined.

    Perusing the sampling of articles above will lay the groundwork for much of what we'll be showing you on the pages ahead.  But to reiterate some of what we explained in our initial coverage of the RV770, AMD is touting the GPU as the first solution to offer 1 TFLOPS of compute power, with higher clocked and multi-GPU offerings capable of even more.

    AMD acheived this feat by increasing the population of the architecture's SP count from 320 on the older RV670 to a 800 on the RV770. AA and Z/Stencil performance were enhanced as well, and the number of texture units was increased from 16 to 40. The 800 stream processing units are grouped in a new SIMD core layout, and the texture units, ROPs, and cache have been restructured to minimize transistor count, while also increasing performance. With the RV770, AMD claims that the SPs in the GPU offer 40% more performance per square millimeter that the previous generation, and that more aggressive clock gating offers improved performance per watt as well. Likewise, the newly streamlined design of the RV770 texture units reportedly offer 70% more performance per square mm with double the texture cache bandwidth and large increases in 32- and 64-bit filter rates.

    The Underlying Technology

    Although the cards look similar and follow a similar design philosophy, the Radeon HD 4870 X2 differs from AMD's previous dual-GPU based Radeon HD 3870 X2 in a number of ways.

    As the above diagram shows, the Radeon HD 3870 X2 featured a pair of GPUs--in its case, RV670s--linked together via a PCI Express gen 1 bridge and a CrossFire bridge interconnect with .9GB/s of peak bandwidth. In total, the design offered an aggregate 6.8GB/s of total interconnect bandwidth across the card.

    The Radeon HD 4870 X2 is quite different, however. Of course, the card is built around a new generation of GPUs, namely the RV770. The card is powered by two of the very same GPUs used to power the Radeon HD 4870. They are also linked together by the very same .9GB/s CrossFire bridge interconnect, but the on-board switch used on the Radeon HD 4870 X2 is PCI Express gen 2 based and hence offers twice the bandwidth. Also note that the RV770 GPU features a new sideport interface that offers another 5GB/s of bandwidth between the two GPUs, each way. The combination of a new gen 2 switch and the sideport interface result in a total aggregate interconnect bandwidth on the Radeon HD 4870 X2 of 21.8GB/s, which is more than 3X that of the 3870 X2.

    We should note, however, the additional bandwidth afforded by the new sideport is not exploited by current software and applications. Representatives from ATI have informed us that future applications should benefit from the sideport, but they didn't explain exactly how or when. We suspect the sideport may enable AMD to develop new multi-GPU rendering modes, or perhaps enable higher performance in certain stream computing applications. Time will tell.

    If you look at the breakdown above, the Radeon HD 4870 X2 isn’t simply two Radeon HD 4870s fused together on a single PCB. The GPUs on the Radeon HD 4870 X2 will be clocked at a minimum of 750MHz and the X2’s gigantic frame buffer memory will be clocked 900MHz (3.6Gpb/s GDDR5 effective), which is similar to the single GPU Radeon HD 4870.  But the X2 features double the amount of frame buffer memory, which could help performance at higher resolutions, and it's also outfitted with a gen 2 PCI Express switch.

    The Radeon HD 4870 X2's main features and benefits are outlined on the slide above. As you can see, the cards offers up to 2.4 TFLOPS of compute power with its 750MHz core GPU clock and 1600MHz (800 x 2) stream processors. Its 2GB (1024MB per GPU) is clocked at 900MHz, which results in a 3.6Gbps GDDR5 data rate, and total memory bandwidth is 230GB/s (115GB/s x 2). With all that horsepower under the hood, the card has a max board power of 285 watts.

    As the old saying goes, "But wait! There's More!" AMD has also informed us that they have a bit of a surprise in the works. A Radeon HD 4850 X2 card that utilizes less expensive GDDR3 RAM is also planned. The Radeon HD 4850 X2's primaary tech specs are outlined in the slide above. With an expected $399 MSRP, the Radeon HD 4850 could wind up being an attractive option in the current 3D graphics landscape and may put even more price pressure on NVIDIA. We hope to have the 4850 X2 in the lab in a few weeks, and will reveal all of its juicy details then.  Expected availabilit is sometime in September.

    A Closer Look At The Cards

    Upon initial inspection, the Radeon HD 4870 X2 looks much like the Radeon HD 3870 X2, just with different PCB coloring. The card features a dark, black PCB with an industrial looking image of bolts and the Radeon logo emblazoned on the fan shroud. Flip the card over, and as you probably expect, the complexity of the design shows through.


    Palit Radeon HD 4870 X2

    We acquired cards from HIS and Palit for this article, both of which are pictured here. In terms of their features and specifications, the Palit and HIS Radeon HD 48070 X2 cards don't differ from ATI's reference design, save for a couple of decals and their accessory bundles.

    As we’ve already mentioned, the Radeon HD 4870 X2 is powered by a pair of 750MHz RV770 GPUs, the same chips used on the Radeon HD 4870 and 4850. The two GPUs are linked together on the PCB through a PCI Express 2.0 fan-out switch from PLX. That switch takes the 16 PCI express lanes coming from the PEG slot and distributes them to both of the GPUs.

    Like the Radeon HD 3870 X2, the new 4870 X2 has only a single CrossFire edge connector along the top of its PCB. It has only one because the other connection is already utilized on the PCB as an interconnect between the on-board GPUs.


    HIS Radeon HD 4870 X2

    Each of the GPUs on the Radeon HD 4870 X2 has its own 1GBMB frame buffer, for a total of 2GB of on-board memory. As you can see, the entire assembly is quite large and results in a 10.5” PCB – a little longer than a standard ATX motherboard. The cooler used on the card is much like previous offerings, but there are some noteworthy elements to the design. Each of the GPUs gets its own heatsink, as do the surrounding switch and RAM. The squirrel-cage type fan draws air in through a hole at the rear of the card, blows air across the heatsinks, and expels it from the system through vents in the mounting plate.

    Like the other members of the Radeon HD 4800 series, the ATI Radeon HD 4870 X2 has a pair of dual-link DVI outputs, and an HD video output. One of the DVI outputs can be converted to an HDMI output with audio using an included adapter.

    The Palit samples we received did not come in full retail trim, so we can't comment on the included bundle at this time.  The HIS card, however, was retail-ready and included a drive CD and manuals, a CrossFire bridge connector, a DVI-to-VGA adapter, a DVI-to-HDMI adapter, an S-Video to composite adapter, an HD component output dongle, a Molex-to-PCI Express power adapter and an HIS case badge.

    Our Test Systems and 3DMark06

    HOW WE CONFIGURED THE TEST SYSTEMS: We tested all of the graphics cards used in this article on either an Asus nForce 790i SLI Ultra based Striker II Extreme motherboard (NVIDIA GPUs) or an X48 based Asus P5E3 Premium (ATI GPUs) powered by a Core 2 Extreme QX6850 quad-core processor and 2GB of low-latency Corsair RAM. The first thing we did when configuring these test systems was enter their respective BIOSes and set all values to their "optimized" or "high performance" default settings. Then we manually configured the memory timings and disabled any integrated peripherals that wouldn't be put to use. The hard drive was then formatted, and Windows Vista Ultimate was installed. When the installation was complete we fully updated the OS, and installed the latest DX10 redist and various hotfixes, along with the necessary drivers and applications.

    HotHardware's Test Systems
    Intel and NVIDIA Powered

    Hardware Used:
    Core 2 Extreme QX6850 (3GHz)

    Asus Striker II Extreme
    (nForce 790i SLI Ultra chipset)

    Asus P5E3 Premium
    (X48 Express)

    Radeon HD 4870 X2 (x2)
    Radeon HD 4870 (x2)
    Radeon HD 4850 (x2)
    Radeon HD 3870 X2 (x2)
    GeForce 9800 GTX+ (x2)
    GeForce 9800 GTX (x3)
    GeForce 9800 GX2 (x2)
    GeForce GTX 260
    GeForce GTX 280 (x3)

    2048MB Corsair DDR3-1333 C7
    (2 X 1GB)

    Integrated Audio
    Integrated Network

    Western Digital "Raptor" 74GB
    (10,000RPM - SATA)

    Relevant Software:

    Windows Vista Ultimate SP1
    DirectX June 2008 Redist

    NVIDIA Forceware v177.39 / v177.83
    ATI Catalyst v8.8b

    Benchmarks Used:
    3DMark06 v1.0.2
    3DMark Vantage v1.0.1
    Unreal Tournament 3 v1.2*
    Crysis v1.2*
    Half Life 2: Episode 2*
    Enemy Territory: Quake Wars*

    * - Custom Benchmark

    Futuremark 3DMark06
    Synthetic DirectX Gaming


    3DMark06 is a synthetic benchmark, designed to simulate DX9-class game titles. This version differs from the earlier 3Dmark05 in a number of ways, and includes not only Shader Model 2.0 tests, but Shader Model 3.0 and HDR tests as well. Some of the assets from 3DMark05 have been re-used, but the scenes are now rendered with much more geometric detail and the shader complexity is vastly increased. Max shader length in 3DMark05 was 96 instructions, while 3DMark06 ups that number to 512. 3DMark06 also employs much more lighting and there is extensive use of soft shadows. With 3DMark06, Futuremark has also updated how the final score is tabulated. In this latest version of the benchmark, SM 2.0 and HDR / SM3.0 tests are weighted and the CPU score is factored into the final tally as well.

    The Radeon HD 4870 X2 was predictably strong in 3DMark06. The overall score for the default benchmark doesn't tell us very much, however, as the test is CPU limited.  If we tunnel down and look at the individual test results though, they better explain what's happening here.

    The less taxing Shader Model 2.0 portion of the benchmark is mostly CPU bound as well.  The spread in the Shader Model 3.0 / HDR test, however, is somewhat more pronounced.  As you can see, the Radeon HD 4870 X2 finishes at, or very near, the top of the charts depending on the configuration tested.  Based on what we see here, expect the 3DMark06 world record to be broken in the next few days by a pair of heavily overclocked Radeon HD 4870 X2 cards.  The 4870 X2 CrossFire configuration put up the best overall score for a "stock" configuration we have seen to date.

    3DMark Vantage

    Futuremark 3DMark Vantage
    Synthetic DirectX Gaming

    3DMark Vantage

    The latest version of Futuremark's synthetic 3D gaming benchmark, 3DMark Vantage, is specifically bound to Windows Vista-based systems because it uses some advanced visual technologies that are only available with DirectX 10, which y isn't available on previous versions of Windows.  3DMark Vantage isn't simply a port of 3DMark06 to DirectX 10 though.  With this latest version of the benchmark, Futuremark has incorporated two new graphics tests, two new CPU tests, several new feature tests, in addition to support for the latest PC hardware.  We tested the graphics cards here with 3DMark Vantage's Extreme preset option, which uses a resolution of 1,920 x 1,200, with 4X anti-aliasing and 16X anisotropic filtering.

    Futuremark's latest addition to the 3DMark franchise, the DX10-based 3DMark Vantage, behaved very differently than the older version of the benchmark.  In this test, the deltas separating the different configurations are huge.  As you can see, the Radeon HD 4870 X2 manhandles any other single graphics card in the list.  And when running in tandem, a pair of Radeon HD 4870 X2 cards bests almost every other configuration, save for a trio of GeForce GTX 280 cards.  

    As we look deeper into the 3DMark Vantage results, the individual GPU tests tell essentially the same story.  Although the framerates are different, the overall trends in the data are the same.  The Radeon HD 4870 X2 outpaces every other single card configuration and only the GeForce GTX 280 3-way SLI setup is faster.

    Half Life 2: Episode 2

    Half Life 2: Episode 2
    DirectX Gaming Performance

    Half Life 2:
    Episode 2

    Thanks to the dedication of hardcore PC gamers and a huge mod-community, the original Half-Life was one of the most successful first person shooters of all time. And courtesy of an updated game engine, gorgeous visuals, and intelligent weapon and level designs, Half Life 2 became just as popular.  Episode 2 - the most recent addition to the franchise - offers a number of visual enhancements including better looking transparent texture anti-aliasing. These tests were run at resolutions of 1,920 x 1,200 and 2,560 x 1,600 with 4X anti-aliasing and 16X anisotropic filtering enabled concurrently.  Color correction and HDR rendering were also enabled in the game engine as well.  We used a custom recorded timedemo to benchmark all cards for these tests.

    Our custom Half Life 2: Episode 2 benchmark was no match for the Radeon HD 4870 X2.  As the results show, the new Radeon HD 4870 X2 is clearly the fastest single graphics card in this game and pairing up two cards in a CrossFire X configuration only serves to increase performance.  At the highest resolution, the 4870 X2 is bested by a couple of NVIDIA SLI configurations, but when running a pair of Radeon HD 4870 X2s in CrossFire, they can't be touched--no other setup came close when everything was maxed out.

    Unreal Tournament 3

    Unreal Tournament 3
    DirectX Gaming Performance

    Unreal Tournament 3

    If you're a long-time PC gamer, the Unreal Tournament franchise should need no introduction.  UT's fast paced action and over the top weapons have been popular for as long as Epic has been making the games.  For these tests, we used the latest addition to the franchise, Unreal Tournament 3.  The game doesn't have a built-in benchmarking tool, however, so we enlisted the help of FRAPS here.  These tests were run at resolutions of 1,920 x 1,200 and 2,560 x 1,600 with no anti-aliasing or anisotropic filtering enabled, but with the UT3's in game graphical options set to their maximum values, with color correction enabled.

    Unreal Tournament 3 is largely CPU bound, even at a resolution 1920x1200.  With the game running at 2560x1600 though (the blue bars in the graph), things spread out a bit more.  At that resolution, the Radeon HD 4870 X2 is the fastest of all the single-card configurations and it hangs with a GTX 260 SLI rig.  In a dual-card CrossFireX configuration, a pair of 4870 X2 cards also puts up the best score bar none, but the GeForce GTX 200 series SLI setups are right there with it, finishing only a couple of frames per second behind.

    Enemy Territory: Quake Wars

    Enemy Territory: Quake Wars
    OpenGL Gaming Performance

    Enemy Territory:
    Quake Wars

    Enemy Territory: Quake Wars is Based on a radically enhanced version of id's Doom 3 engine and viewed by many as Battlefield 2 meets the Strogg, and then some.  In fact, we'd venture to say that id took EA's team-based warfare genre up a notch or two.  ET: Quake Wars also marks the introduction of John Carmack's "Megatexture" technology that employs large environment and terrain textures that cover vast areas of maps without the need to repeat and tile many smaller textures.  The beauty of megatexture technology is that each unit only takes up a maximum of 8MB of frame buffer memory.  Add to that HDR-like bloom lighting and leading edge shadowing effects and Enemy Territory: Quake Wars looks great, plays well and works high end graphics cards vigorously.  The game was tested with all of its in-game options set to their maximum values with soft particles enabled in addition to 4X anti-aliasing and 16x anisotropic filtering.

    Our custom Enemy Territory:Quake Wars benchmark tells essentially the same story as the previous games tests.  The new Radeon HD 4870 X2 put up the best scores for any single graphics card configuration.  The game did scale with two Radeon HD 4870 X2 cards running in CrossFireX mode as well, but not enough to fend off NVIDIA's flagship offerings.  In this game, the GeForce GTX 280 SLI configuration takes the top spot at 1920x1200, and the 3-way GTX 280 SLI setup takes the lead at 2560x1600.

    Crysis v1.2

    Crysis v1.2
    DirectX 10 Gaming Performance


    If you're at all into enthusiast computing, the highly anticipated single player, FPS smash-hit Crysis, should require no introduction. Crytek's game engine produces some stunning visuals that are easily the most impressive real-time 3D renderings we've seen on the PC to date.  The engine employs some of the latest techniques in 3D rendering like Parallax Occlusion Mapping, Subsurface Scattering, Motion Blur and Depth-of-Field effects, as well as some of the most impressive use of Shader technology we've seen yet.  In short, for those of you that want to skip the technical jib-jab, Crysis is a beast of a game.  We ran the full game patched to v1.2 with all of its visual options set to 'High' to put a significant load on the graphics cards being tested  A custom demo recorded on the Island level was used throughout testing.

    It appears Crysis would not scale past two GPUs with the Radeon HD 4800 series cards.  The Radeon HD 4870 X2 performs right on par with a pair of Radeon HD 4870 cards running in CrossFire mode.  Pairing up the Radeon HD 4870 X2 cards in a four-GPU CrossFireX configuration didn't help performance, however.  Overall, all of the NVIDIA SLI configurations put up better scores in this test.  We expect future driver revisions to significantly help the Radeon HD 4870 X2 CrossFireX configuration here though.

    SD and HD Video Performance

    We also did some testing of the Radeon HD 4870 X2's UVD video processing engine, in terms of both image quality and CPU utilization with some HQV and H.264 playback tests.

    Video Playback Performance: SD and HD
    HQV and H.264

    HQV is comprised of a sampling of SD video clips and test patterns that have been specifically designed to evaluate a variety of interlaced video signal processing tasks, including decoding, de-interlacing, motion correction, noise reduction, film cadence detection, and detail enhancement. As each clip is played, the viewer is required to "score" the image based on a predetermined set of criteria. The numbers listed below are the sum of the scores for each section. We played the HQV DVD using the latest version of Cyberlink's PowerDVD HD, with hardware acceleration for AMD AVIVO HD and NVIDIA PureVideo HD extensions enabled.


    Both ATI's and NVIDIA's latest GPUs have no trouble with SD video playback.  All three of the cards put up near perfect scores in the HQV test.  In case you're not familiar with HQV, 130 points is the maximum score attainable.  At 128 points, a PC equipped with either of these graphics cards plays back DVD video at quality levels better than the vast majority of set-top DVD players on the market.

    We should note, however, the Radeon HD 4870 X2 did suffer from some visual artifacts when we scaled the DVD video to anything higher than its native resolution.  We suspect the new DVD scaler that is part of the UVD 2 engine had an adverse affect on the specialized HQV tests.  The effect was less pronounced that what we saw in our initial evaluation of the HD 4800 series, and seemed to only affect about 20% of the image through the center of the screen.

    Next we conducted a test using an H.264 encoded movie trailer clip for "Beowulf" which is available for download on Apple's QuickTime HD website.  The CPU utilization data gathered during these tests was taken from Windows Vista's built-in Performance Monitor. The graphs show the CPU utilization for a GeForce GTX 280, a Radeon HD 4870, and a Radeon HD 4870 X2 using PowerDVD HD to playback the QuickTime clip.

    GeForce GTX 280

    Radeon HD 4870

    Radeon HD 4870 X2

    With a fast quad-core processor powering our test system and an unencrypted HD video clip being played back, all of the cards we tested had low CPU utilization in this test.  We should note that with hardware acceleration disabled, playing this video clip results in about 12% - 15% average CPU utilization, so there is a marked improvement with both PureVideo HD and UVD 2.  Also note that with encrypted content, like many off the shelf Blu-Ray discs for example, CPU utilization will be measurably higher that what you see here.  However, both platforms should have no trouble playing back high def digital video.

    With that said, the Radeon HD 4870 X2 did consume more CPU resources than the Radeon HD 4870, but an average of 11% should still be considered low.

    Total System Power Consumption

    We'd like to cover a few final data points before bringing this article to a close. Throughout all of our benchmarking and testing, we monitored how much power our test systems were consuming using a power meter. Our goal was to give you all an idea as to how much power each configuration used while idling and under a heavy workload. Please keep in mind that we were testing total system power consumption at the outlet here, not just the power being drawn by the motherboards alone.

    Total System Power Consumption
    Tested at the Outlet

    As you can see, the Radeon HD 4870 X2 isn't going to end up in any "green" PCs.  When either idling or running under a heavy graphics workload, the Radeon HD 4870 X2 consumed more power than another single graphics card, and sometimes more than two single-GPU based graphics cards.  The 4-GPU, Radeon HD 4870 X2 CrossFireX configuration also consumed more power than any other graphics card configuration by a large margin.

    As you probably expect, a graphics configuration that pulls total system power consumption up into the 820+ watt range can get quite hot and run somewhat loud.  We witnessed GPU temperatures over 90ºC according to ATI's drivers with the cards running under load, and idle temps hovered around 80ºC.  We wonder just how accurate the reporting in the driver is, however, as we also recorded heatsink temperatures using an infrared thermometer of about 78ºC.  Regardless, one thing is for certain--the Radeon HD 4870 X2 can get very hot.  We definitely recommend good case cooling if you plan to purchase one of these babies.

    When running under load, the cards' coolers also produce a very noticeable report.  In a single card configuration, the Radeon HD 4870 X2's acoustic profile is about on par with other high-end graphics cards, and even though it was a little louder, we wouldn't consider it bothersome.  With two cards cranking along at nearly full bore, however, the noise output would definitely be a concern for some.

    Our Summary and Conclusion

    Performance Summary: Throughout our entire battery of tests, the new Radeon HD 4870 X2 proved to be a top performer, whether running in a single-card configuration or in a dual-card, four-GPU, CrossFireX configuration.  In the games and applications we tested, the Radeon HD 4870 X2 outperformed every other single graphics card, including the GeForce GTX 280.  Generally speaking, the 4870 X2 was on-par with or marginally faster than a Radeon HD 4870 CrossFire setup and somewhat faster than a GeForce GTX 260 SLI configuration in most benchmarks, although the GTX 260 SLI rig did catch up with it a couple of times.  Depending on how well the Radeon HD 4870 X2 CrossFireX configuration scaled, it too was one of the fastest multi-GPU configurations available, but a pair or trio of GeForce GTX 280 cards were faster in a few instances. 


    Make no mistake, the new Radeon HD 4870 X2 marks ATI's return to the top of the 3D graphics food chain.  It took a few years, but through steady improvements in multi-GPU software support, and a new strategy regarding the design and manufacture of high-end graphics cards that utilizes two mid-sized chips in lieu of a single monolithic one, AMD was able to produce a graphics card capable of outpacing the best NVIDIA currently has to offer.

    As we stated in our conclusion when we first took a look at AMD's previous two-GPU flagship, the Radeon HD 3870 X2, because the Radeon HD 4870 X2 is essentially “CrossFire on a card”, the X2’s performance is ultimately determined by how well the card’s drivers scale in a particular game. If a new game hits store shelves and the drivers don’t recognize its executable, the $549 Radeon HD 4870 X2 will perform much like a single-GPU Radeon HD 4870 that is approximately half the price.  On many occasions since the launch of the Radeon HD 3870 X2, AMD has assured us their software team will continually be working to try to minimize this situation, but it quite possibly could be an issue at some point in time no matter how hard they work, unless a universally compatible multi-GPU rendering technique is devised. This is something you must be aware of if you’re contemplating the purchase of Radeon HD 4870 X2.

    Expect Radeon HD 4870 X2 cards to be available immediately for about $549.  At that price, the Radeon HD 4870 X2 is certainly not for everyone and it is the most expensive consumer level graphics card on the market.  But prices in the graphics card space have been on downward spiral for weeks and we suspect this card won't remain at that price for long, even if NVIDIA doesn't release something new to steal some of ATI's thunder.  A GTX 280, for example, may not perform as well as the 4870 X2 overall, but it is currently about $100-$150 less expensive (after rebates) and users won't have to worry about multi-GPU scaling issues.  Although the Radeon HD 4870 X2 is an all-around faster card, the price difference and the benefits of the GeForce GTX 280's single-GPU design still make it an attractive option for hardcore enthusiasts in our opinion.

    In the end though, the Radeon HD 4870 X2 simply rocks.  We wish it didn't run quite as hot and that its cooler was a bit quieter, but those are things ATI's partners will likely address.  Welcome back to ultra high-end AMD.  It's obvious you have worked hard, and your efforts have paid off.  The Radeon HD 4870 X2 is a 3D graphics tour de force.

    • Extreme Performance
    • CrossFireX Support
    • UVD 2 Video Engine
    • DirectX 10.1 Support
    • 2GB Frame Buffer
    • Card Runs HOT
    • Cooler Can Be Loud
    • Performance Ultimately Determined By Drivers

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