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ATI Radeon HD 3870 and 3850: 55nm RV670
Date: Nov 15, 2007
Author: Marco Chiappetta
Introduction and Related Information

When the R600 GPU hit the scene last May in the form of the Radeon HD 2900 XT, it wasn't very well received by enthusiasts for a few key reasons.  For one, the Radeon HD 2900 XT generally consumed more power and generated more heat than NVIDIA’s already well established GeForce 8800 GTS.  In addition, the 2900 XT was also louder, more expensive, and also didn't quite perform as well as the 8800 GTS, not to mention it was missing UVD support.  A home run product the Radeon HD 2900 XT was not.

From a technical standpoint, however, the R600 was promising.  It had full DX10 support, top notch image quality, gobs of memory bandwidth, and a number of innovations like HDMI output with audio and new anti-aliasing modes.  After testing the Radeon HD 2900 XT and watching it mature in the marketplace these past few months, we couldn't help but wonder how the R600 would have been received had AMD built the chips using a more advanced manufacturing process that could help mitigate some of its fundamental shortcomings.

We can stop wondering now it seems.  Today is the day AMD has chosen to officially unveil the RV670 GPU, a derivative of the R600, manufactured using a 55nm process.  The RV670 will be the GPU that powers the new ATI Radeon HD 38x00 series of graphics cards.  However, we should point out that the RV670 isn’t a straight-up shrink of the 90nm R600.  In this iteration of the 55nm RV670, AMD has also tweaked the GPU in a few areas in an effort to increase relative performance and efficiency.

We’ve had a quartet of RV670-based cards in house for a short while and have put them through the wringer with an entirely new and up-to-date test-bed running Windows Vista Ultimate and powered by a Quad-Core Intel Core 2 Extreme CPU.  Read on for the full scoop...


ATI Radeon HD 38x0
Features & Specifications

666 million transistors on 55nm fabrication process

256bit 8-channel GDDR3/4 memory interface

Ring Bus Memory Controller

  • Fully distributed design with 512-bit internal ring bus for memory reads and writes
  • Optimized for high performance HDR (High Dynamic Range) rendering at high display resolutions

Unified Superscalar Shader Architecture

  • 320 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 80 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

Full support for Microsoft DirectX 10 / 10.1 

  • Shader Model 4.0
  • Geometry Shaders
  • Stream Output
  • Integer and Bitwise Operations
  • Alpha to Coverage
  • Constant Buffers
  • State Objects
  • Texture Arrays

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 (up to 8 samples per pixel)
  • Up to 24x Custom Filter Anti-Aliasing (CFAA) for improved quality
  • Adaptive super-sampling and multi-sampling
  • Temporal anti-aliasing
  • Gamma correct
  • Super AA (CrossFire configurations only)
  • All anti-aliasing features compatible with HDR rendering

CrossFire Multi-GPU Technology

  • Scale up rendering performance and image quality with 2 or more GPUs
  • Integrated compositing engine
  • High performance dual channel interconnect
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
  • Bicubic 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

ATI Avivo HD Video and Display Platform

  • 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 dual-link DVI display outputs
    • Each supports 18-, 24-, and 30-bit digital displays at all resolutions up to 1920x1200 (single-link DVI) or 2560x1600 (dual-link DVI)
    • Each includes a dual-link HDCP encoder with on-chip key storage for high resolution playback of protected content
  • Two integrated 400 MHz 30-bit RAMDACs
    • Each supports analog displays connected by VGA at all resolutions up to 2048x1536
  • HDMI output support
    • Supports all display resolutions up to 1920x1080
    • Integrated HD audio controller with multi-channel (5.1) AC3 support, enabling a plug-and-play cable-less audio solution
  • Integrated Xilleon HDTV encoder
    • Provides high quality analog TV output (component / S-video / composite)
    • Supports SDTV and HDTV resolutions
    • Underscan and overscan compensation
  • HD decode for H.264/AVC, VC-1, DivX and MPEG-2 video formats
    • Flawless DVD, HD DVD, and Blu-Ray playback
    • Motion compensation and IDCT (Inverse Discrete Cosine Transformation)
  • HD video processing
    • Advanced vector adaptive per-pixel de-interlacing
    • De-blocking and noise reduction filtering
    • Edge enhancement
    • Inverse telecine (2:2 and 3:2 pull-down correction)
    • Bad edit correction
    • High fidelity gamma correction, color correction, color space conversion, and scaling
  • 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

PCI Express 2.0 x16 bus interface

OpenGL 2.0 support



There is some pertinent information related to today's launch available on our site that we recommend you read, to get familiar with AMD's new ATI RV670 GPU, their previous GPU architectures, and their key features. The Radeon HD 3870 and 3850 are based on a GPU derived from of the R600, and as such they have a number of key features in common that we've already covered in much greater detail that we will here today. The articles we suggest you peruse include:

If you haven't already done so, we recommend scanning through our 2x00 series coverage, our CrossFire Multi-GPU technology preview, and the Radeon X1950 Pro with Native CrossFire article. In those four pieces, we cover a large number of the features offered by the new Radeon HD 38x0 series and explain many of the features of DirectX 10. We recommended reading these articles because there is quite a bit of background information in them that'll make it easier to digest what we're going to showcase here today.

The 55nm RV670 GPU Architecture


As we’ve already mentioned, the RV670 GPU borrows heavily from the R600 that came before it.  The core technology in each GPU architecture is fundamentally very similar.  But with the RV670, AMD has made a number of changes designed to boost performance in certain areas as well as enhance power efficiency.  We covered the R600 architecture in-depth in our Radeon 2900 XT launch article, so we won’t go in-depth again here, but we do want to point out some pertinent information.  What we have for you below are a number of slides taken from an AMD presentation explaining the key benefits of the RV670 GPU and the products built around it – the Radeon HD 3870 and Radeon HD 3850.


Radeon HD 3870 X2? Yes, a single card with dual-GPUs is coming in '08

One of the RV670’s stand-out features is full support for DirectX 10.1.  A few weeks back, news broke that Microsoft would be releasing DX10.1 with Vista SP1 in early 2008, and that the current generation of DX10 GPUs would not fully support the new features brought forth with the update.  The merits of the new features inherent to the DX10.1 update are still in question, but AMD decided to support them in hardware anyway.

As for the fundamental blocks inside the GPU, RV670 doesn’t differ very much from R600.  The RV670 still has 320 stream processing units, 16 texture units, and 16 ROPs.  The RV670, however, does away with the 1024-bit internal ring-bus memory controller in favor of a 512-bit variant.  And its memory interface has also been pared down from 512-bits to 256-bit.  From high-level perspective, these changes sound-like downgrades, but other tweaks to the GPU negate a massive loss of internal and external bandwidth.  While the R600 uses 8, 64-bit memory channels, the RV670 doesn’t simply use 4, 64-bit channels.  Instead the new GPU uses 8, 32-bit channels to improve the granularity of the data transfer, which in turn improves relative efficiency of the RV670’s memory bus.  There have also been other tweaks, such as improved memory arbitration logic and higher memory clocks on HD 3870 in particular.  And as you’ll see a little later, the net performance profile between R600 and RV670 is very competitive.

Overall improvements have also been made with RV670. Since the Radeon HD 2900 XT was out in the wild before RV670 was back from the fab, AMD has time to better evaluate the performance characteristics of the R600 and the bottlenecks of the architecture.  Much of what the company learned from this allowed AMD to tweak the RV670’s design in order to minimize the bottlenecks as much as possible.  Another area of focus with the RV670 was improving the handling of latency bound tasks to schedule work more effectively. The net result of the improvements is that despite halving the memory-bus width, the RV670 is sometimes faster than HD 2900.


CrossFireX - When Two Video Cards Just Won't Do

Other changes to the RV670 include a more advanced manufacturing process, the introduction of PowerPlay on the desktop, and support for PCI Express 2.0 and CrossFireX.  Moving to TSMC’s advanced 55nm manufacturing process to build the 666M transistor RV670 results in nearly twice the transistor density and a much smaller die than R600.  In fact, the RV670 is less than half the size of the R600 192mm2 versus 408mm2.

The new GPU also takes advantage of ATI’s PowerPlay technology which down-clocks or disables parts of the GPU when not in use, or when maximum performance is not necessary. The combination of PowerPlay and the new manufacturing process drastically reduces the RV670’s power requirements, especially in comparison to the R600.

The RV670 also supports the PCI Express 2.0 standard which doubles the bandwidth of the GPU’s serial link interface when used with a compatible chipset.  With CrossFireX, users are able to link two, three, or even four cards together to increase performance.  To utilize three and four card CrossFireX configuration, you’ll need a motherboard with the correct slot configuration and proper drivers.  Motherboards with the necessary PEG slots are already available.  The drivers, however, won’t arrive until later this year or early in 2008.

The Radeon HD 3870 and 3850 Cards


The actual RV670-based Radeon HD 3870 and 3850 cards feature new PCB and heatsink cooler designs that are welcome changes from the Radeon 2900 XT.


ATI Radeon HD 3870

The Radeon HD 3870 and 3850 are both about a half an inch shorter than the Radeon HD 2900 XT, and should have no clearance issues in any standard case.  The Radeon HD 3870 pictured here features 512MB of GDDR4 memory clocked at 1126MHz (2.25GHz DDR), which results in just over 72GB/s of peak bandwidth. The card’s GPU is clocked at 777MHz – 37MHz higher than reference 2900 XT cards.

The Radeon HD 3870’s cooler is a dual-slot design, which thankfully is much quieter than the 2900 XT’s as well.  We should note that when first powered on, the fan on the Radeon HD 3870 spins up and produces an significant amount of noise, but it quickly spins down and is near silent.  Over the course of testing, it never spun up to top speed – even with two cards installed into a basic mid-tower chassis.  We’re also told that some AIB partners are planning to produce single-slot versions of the HD 3870, but we have yet to see one for ourselves.



ATI Radeon HD 3850

As you probably expected, the Radeon HD 3850 is based on the same PCB as the 3870, but it has lower GPU and memory clock speeds.  The Radeon HD 3850 features a 670MHz GPU and 256MB of 830MHz (1.66GHz DDR) GDDR3 memory for a total of 52GB/s of peak bandwidth. Unlike the HD 3870, however, all reference-clocked HD 3850 cards feature a quiet single-slot cooler.

Something you may have also noticed is that both the Radeon HD 3870 and HD 3850 require only a single 6-pin supplemental PCI Express power connection.  Thanks to the RV670’s 55nm manufacturing process and architectural tweaks, cards based on the GPU require much less power than the R600 and can get by with only a single additional power connection.  Does that GPU look tiny by today's standards, or what?

Sapphire's Radeon HD 38x0s

The current trend in the GPU business is to ‘hard launch’ a product; that is the goal is to have retail-ready products available for purchase the moment they’re unveiled.  To coincide with AMD’s announcement of the new Radeon HD 3870 and HD 3850, we actually received not one, but two cards in full retail trim courtesy of AMD’s premiere ATI board partner, Sapphire.


The Sapphire Radeon HD 3870

What you see pictured above is the Sapphire Radeon HD 3870.  The actual card’s specifications don’t differ from ATI’s reference design, and as such, performance between the two is identical.  Sapphire’s card also uses the same dual-slot cooler, albeit with a custom Sapphire-branded decal.  Just like ATI’s reference design, the Sapphire Radeon HD 3870 pictured here sports an RV670 GPU and 512MB of frame buffer memory.


The Sapphire Radeon HD 3850

Sapphire’s Radeon HD 3850 card is also virtually identical to ATI’s reference design.  The Sapphire Radeon HD 3850 pictured here sports the same GPU, PCB, and memory configuration as ATI-branded cards.  Where Sapphire differentiates their cards, however, is with some value added bundled software. Sapphire’s Radeon HD 3800 series cards ship with Valve’s excellent Black-Box gaming suite, a full retail copy of 3DMark06, and full versions of Cyberlink’s PowerDVD and DVD Suite.

We should also note that Sapphire has an ‘Ultimate’ Edition silent Radeon HD 3850 in the works. The Ultimate Edition will sport a passive, single-slot cooler.  We haven’t gotten our hands on one yet, but we suspect a silent, single-slot, Radeon HD 3850 is going to be mighty popular with the HTPC crowd.

Test Setup and 3DMark06


HOW WE CONFIGURED THE TEST SYSTEMS: We tested all of the graphics cards used in this article on either an EVGA nForce 680i SLI motherboard (NVIDIA GPUs) or an Asus P5E3 Deluxe (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 the test systems was enter their respective BIOSes and set all values to their "optimized" or "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.

The HotHardware Test System

Core 2 Extreme Powered


Motherboard -

Video Cards -

Memory -

Audio -

Hard Drive

Hardware Used:
Core 2 Extreme QX6850 (3GHz) 

EVGA nForce 680i SLI
nForce 680i SLI chipset

Asus P5E3 Deluxe
X38 Express 

Radeon HD 3870 (2)
Radeon HD 3850 (2)
Radeon HD 2900 XT (2)
Radeon HD 2600 XT (2)
GeForce 8800 GTX (2)
GeForce 8800 GT (2)

GeForce 8800 GTS (2)
GeForce 8600 GTS (2)

2048MB Corsair PC2-6400C3
2 X 1GB
2048MB Corsair DDR3-1333 C7
2 X 1GB

Integrated on board

Western Digital "Raptor"

74GB - 10,000RPM - SATA

OS - 

DirectX -

Video Drivers

Synthetic (DX) -
DirectX -
DirectX -
DirectX -
DirectX -
OpenGL -

Relevant Software:

Windows Vista Ultimate

DirectX 10

NVIDIA Forceware v169.09
ATI Catalyst BETA v8.43

Benchmarks Used:
3DMark06 v1.0.2
Company of Heros - DX10
Crysis - DX10
Half Life 2: Episode 2*
Enemy Territory: Quake Wars*

* - Custom Test
(HH Exclusive demo)

Performance Comparisons with 3DMark06 v1.0.2
Details: www.futuremark.com/products/3dmark06

3DMark06 is the most recent addition to the 3DMark franchise. This version differs from 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 as well. 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.

According to 3DMark06, the new Radeon HD 3870 performs about on par with the 2900 XT and just behind the relatively new GeForce 8800 GT. And as expected, the Radeon HD 3850 finishes just behind the higher-clocked HD 3870.

The performance trend doesn't change all that much when running the new Radeons in dual-card CrossFire configurations.  Here, the new Radeon HD 3870 and 3850 cards scale very well and put up scores well ahead of their NVIDIA-based competition.  If you look at the individual results, however, you'll notice their lead comes mostly from a dominant performance in the SM 2.0 tests and not the more taxing SM 3.0 / HDR tests. 

Half Life 2: Episode 2


Performance Comparisons with Half-Life 2: Episode 2

Details: www.half-life2.com

Half Life 2:

Episode 2

Thanks to the dedication of hardcore PC gamers and a huge mod-community, the original Half-Life became one of the most successful first person shooters of all time.  And thanks to an updated game engine, gorgeous visual, and intelligent weapon and level design, Half Life 2 became just as popular.  Episode 2 offers a number of visual enhancements including better looking transparent texture anti-aliasing. These tests were run at resolutions of 1,280 x 1,024, 1,600 x 1,200 and 1,920 x 1,200 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 file to benchmark all cards in this test.

In a single-card configuration, the Radeon HD 3870 slightly outperforms the Radeon HD 2900 XT in our custom Half Life 2: Episode 2 benchmark.  The HD 3850, however, finished behind the 2900 XT due to its smaller frame buffer and lower frequencies.  But all of the Radeons fall victim to NVIDIA's hardware here.


The Radeon HD 3870's lead over the 2900 XT increases when running in dual-card Crossfire mode, and the HD 3850's deficit is significantly reduced due to better scaling.  But once again the GeForce 8800 series cards come out on top at every price point. 

Company of Heroes


Performance Comparisons with Company of Heroes

Details: www.companyofheroesgame.com

Company of Heroes

Relic Entertainment's World War II era real-time strategy game Company of Heroes was originally released as a DirectX 9 title for Windows.  But recent upates to the game have incorporated support for new DirectX 10 features that improve image quality and enhance the game's finer graphical details.  The game features a built-in performance test which which we used to attain the results below. Our Company of Heroes tests were run at resolutions of 1,280 x 1,024, 1,600 x 1,200 and 1920 x 1200 with 4X anti-aliasing and all of the game's image-quality related options set to their maximum values.

Running Company of Heroes in DirectX 10 mode puts a major strain on all of the graphics cards we tested.  The performance trend we've witnessed up to this point continues to play out in this game, with the HD 3870 edging out the older 2900 XT, but trailing NVIDIA's GeForce 8 series hardware.



Switching to a dual-card CrossFire configuration gives the Radeon HD cards a nice boost in performance, and the Radeon HD 3870 CrossFire rig is able to overtake the GeForce 8800 GTS and GT SLI systems at the higher resolutions by a few frames per second.

Enemy Territory: Quake Wars

Performance Comparisons with ET: Quake Wars

Details: www.enemyterritory.com

Enemy Territory: 
Quake Wars

Enemy Territory: Quake Wars is Based on id's radically enhanced 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 extremely large environment and terrain textures that cover vast areas of maps without the need to repeat and tile many small 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.

The new Radeon HD 3870 and 3850 perform well in our custom Enemy Territory: Quake Wars benchmark, but once gain fall victim to more powerful NVIDIA hardware at all resolutions.  Historically, NVIDIA's products have performed very well with id's game engines and that trend shows no signs of letting up.

The beta drivers ATI provided with the new Radeon HD 3870 and 3850 had issues with ET: Quake Wars when running in dual-card CrossFire configurations. Both cards lost a significant amount of performance running in CrossFire mode and obviously get hammered by the GeForces.  We should note that we used the ET: Quake Wars compatible hotfix driver available on ATI's website with the Radeon HD 2900 XT CrossFire rig, and it didn't show the massive decreses in performance of the other Radeons, but it's performance didn't scale upwards either.  There is still some driver work to be done here.

Crysis SP Demo

Performance Comparisons with Crysis

Details: www.ea.com/crysis


If you're at all into enthusiast computing, the highly anticipated single player demo of the hot, new, upcoming FPS smash-hit Crysis, should require no introduction. Crytek's game engine visuals are easily the most impressive real-time 3D renderings we've seen on the computer screen 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 HOT.  We ran the SP demo with all of the game's visual options set to 'High' to put a significant load on the graphics cards being tested.

The Radeon HD 3870 and HD 2900 XT take turns edging each other out in Crysis depending on the resolution being tested, and the Radeon HD 3850 finishes just behind them.  The GeForce 8800 cards, however, performed much better here at every resolution.



Here we have another situation where the Radeons' performance don't scale well when running in a CrossFire configuration and the GeForces pull well ahead.  We should also note that running the Radeons in CrossFire moder resulted in numerous flashing textures.  Obviously AMD still has some driver work to do in regards to CrossFire.

Video Performance: SD and HD

Finally, we set out to stress the new GeForce 8800 GT's PureVideo HD video processing engine, in terms of both image quality and CPU utilization with our HQV and H.264 playback tests.

HQV - DVD Video Decoding and Playback Quality

Pure Video HD vs. UVD

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, with hardware acceleration for AMD AVIVO HD and NVIDIA PureVideo HD extensions enabled.



Both ATI's and NVIDIA's current generation GPUs have no trouble with SD video playback.  Both the Radeon HD 3870 and GeForce 8800 GT 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.

H.264 Video Decoding And Playback Performance
Sipping CPU Cycles

Next we conducted quick a test using an H.264 encoded movie trailer clip for "Beowulf" which is available for download on Apple's QuickTime 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 8800 GT and a Radeon HD 3870 using PowerDVD to playback the QuickTime clip.

GeForce 8800 GT

Radeon HD 3870

With a powerful quad-core processor at the heart of our test system and an unencrypted HD video clip being played, both the GeForce 8800 GT and Radeon HD 3870 averaged low, single-digit CPU utilization in this test.  We should note that with hardware acceleration disabled, playing this video clip results in about 12% - 15% CPU utilization, so there is a marked improvement with both PureVideo HD and AVIVO HD.

Overclocking the new Radeons

For our next set of performance metrics, we spent some time overclocking the new Radeon HD 3870 and HD 3850 cards, using the Overdrive utility built into ATI's Catalyst drivers.

A New Overdrive Menu

As you can see, the latest revision of Overdrive is a vast improvement over previous offerings.  This revision of Overdrive now gives users the ability to individually overclock cards when running in CrossFire configurations.  It also has a new built-in test, wider frequency ranges, as well as GPU activity and temperature monitors.


Overclocking the Radeon HD 3870 and 3850

(Fast 3D Video Cards) + Overclocking = Even Faster Cards

To find the Radeon HD 3870's and 3850's peak core and memory frequencies, we slowly raised their respective sliders until we begun to see visual artifacts on-screen while running a game or benchmark, or until our test system was no longer stable

Radeon HD 3870 (Overclocked): GPU=845MHz, Memory=1186MHz
Radeon HD 3850 (Overclocked):
GPU=770MHz, Memory=1040MHz

Radeon HD 3870 (Overclocked): GPU=845MHz, Memory=1186MHz
Radeon HD 3850 (Overclocked): GPU=770MHz, Memory=1040MHz

Ultimately, we were able to take the Radeon HD 3870 up from its stock GPU and memory clock speeds of 777MHz and 1126MHz to 845MHz and 1186MHz, respectively.  The Radeon HD 3850 went from 670MHz (GPU) and 830MHz (Memory) to 770MHz and 1040MHz.  While both cards were overclocked, we re-ran a couple of high-resolution benchmarks and saw significant increases across the board.

Power Consumption and Noise

Before we bring this article to a close, we'd like to cover a few final data points. Throughout all of our benchmarking and testing, we monitored how much power our test system was consuming using a power meter and also took some notes regarding its noise output. Our goal was to give you all an idea as to how much power each configuration used and to explain how loud the configurations were under load. Please keep in mind that we were testing total system power consumption at the outlet here, not just the power being drawn by the video cards alone.

Total System Power Consumption & Acoustics
It's All About the Watts and Decibels

While idling and under load, the new Radeon HD 3970 and 3850 cards consumed significnatly less power than all but the entry level Radeon HD 2600 XT and GeForce 8600 GTS cards.  The design changes and move to a 55nm process paid huge dividens in terms of power consumption.  Keep in mind, the Radeon HD 3870 performs on par with the Radeon HD 2900 XT and GeForce 8800 GTS, while using less power.  That makes the Radeon HD 38x0 series a winner in the performance-per-watt department.  What a difference a few months can make.

In terms of noise output, we're happy to report the new Radeons were barely audible over the noise produced by our test system's CPU cooler, PSU fans, and hard drive.  During normal operation, these cards are significantly quieter than the Radeon HD 2900 XT and are on par with or quieter than NVIDIA's offerings.

Our Summary and Conclusion


Performance Summary: The new Radeon HD 3870 performed much like a Radeon HD 2900 XT.  The two cards generally traded victories over each other depending on the game and resolution being tested.  Due to its smaller frame buffer and lower clock speeds, the Radeon HD 3850's performance was somewhat lower, but in comparison to what are expected to be similarly priced mid-range cards like the Radeon 2600 XT and GeForce 8600 GTS, the Radeon HD 3850’s performance is quite strong.  NVIDIA’s GeForce 8800 GTS, GT, and of course GTX usually performed better than the new Radeons, however.


There is a lot to like about the new Radeon HD 38x0 series.  Both the Radeon HD 3870 and 3850 performed well throughout our entire battery of tests, in terms of framerates and image quality.  Video playback performance was also good and thanks to design tweaks, PowerPlay, and a new 55nm manufacturing process power consumption, temperatures, and noise levels are way down in comparison to the previous generation.  The RV670 GPU also offers support for DirectX 10.1, which is a first in the industry.

According to AMD, the ATI Radeon HD 3870 and Radeon HD 3850 have MSRPs of $219 and $179, respectively.  Both cards should be available immediately.  If these cards end-up being widely available and have actual street prices approaching these MSRPs, we suspect they are going to be very popular this holiday buying season.  Considering how much cheaper they must be to produce than the 2900 XT, we’re sure AMD is hoping for some big numbers.  If street prices end up much higher, however, the Radeon HD 3870 and 3850 face some stiff competition from the GeForce 8800 GT, which outperforms the new Radeons in just about every game engine we tested.  And don’t forget a less expensive 256MB GT is on the way as well.  Fortunately for AMD, the GeForce 8800 GT is tough to find at the moment and it’s selling for much more than its MSRP.

It’s going to take a couple of weeks to see what pricing and availability look like for both AMD and NVIDIA’s latest offerings.  They’re both looking strong though and are worth the upgrade.  If you were waiting for the right moment to jump on the DX10 bandwagon, that time is rapidly approaching.

  • Good Performance
  • Great Power Characterisitcs
  • Quiet
  • Low MSRPs
  • CrossFire Scaling Issues
  • NVIDIA Still Faster Overall

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