iXBT Labs - Computer Hardware in Detail







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July 14, 2008

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Last time we tested RADEON HD 4850 in games. Now we got hold of the higher-end HD 4870 with GDDR5 memory. Even though it has the same architecture and the same number of processing units, we decided to compare it to GeForce GTX 260, its competitor in terms of price.

The complete architecture review is provided in the previous article. So, we'll just repeat specifications of the GPU and the card.


  • Codename: RV770-2
  • Process technology: 55 nm
  • 956 million transistors
  • Unified architecture with an array of common processors for streaming processing of vertices and pixels, as well as other data
  • Hardware support for DirectX 10.1, including new Shader Model 4.1, geometry generation, and stream output
  • 256-bit memory bus: four 64-bit controllers supporting GDDR3/GDDR5
  • Core clock: 750 MHz
  • 10 SIMD cores, including 800 scalar floating-point ALUs (integer and floating-point formats, support for FP32 and FP64 in compliance with IEEE 754)
  • 10 enlarged texture units supporting FP16 and FP32 formats
  • 40 texture address units
  • 160 texture fetch units
  • 40 bilinear filtering units that can filter FP16 textures at full speed, trilinear and anisotropic filtering for all texture formats
  • Dynamic branching in pixel and vertex shaders
  • 16 ROPs supporting antialiasing with programmable sample patterns (over 16 samples per pixel), including FP16 or FP32 formats of the frame buffer. Peak performance is up to 16 samples per cycle (including MSAA 2x/4x and FP16 buffers), 64 samples per cycle in Z only mode
  • Writing results up to eight frame buffers simultaneously (MRT)
  • Integrated support for two RAMDACs, two Dual Link DVIs, HDMI, HDTV, DisplayPort

RADEON HD 4870 Specifications

  • Core clock: 750 MHz
  • Unified processors: 800
  • 40 texture units, 16 blending units
  • Effective memory frequency: 3600 MHz (4*900 MHz)
  • Memory type: GDDR5
  • Memory: 512 MB
  • Memory bandwidth: 115 GB/sec
  • Maximum theoretical fillrate: 12.0 gigapixel per second
  • Theoretical texture sampling rate: 30.0 gigatexel per second
  • 2 x CrossFireX connectors
  • PCI Express 2.0 x16 bus
  • 2 x DVI-I Dual Link, 2560x1600 video output
  • TV-Out, HDTV-Out, support for HDCP, HDMI, DisplayPort
  • Power consumption: up to 160 W (two 6-pin connectors)
  • Two-slot design
  • Recommended price: $299

As you may have noticed, we publish articles related to 48xx series with much delay, for which AMD is to be blamed. Inviting mass media five days prior to the announcement and then shifting the event is pure disrespect to IT reviewers. To all appearances, the marketing department forgot that users and retailers do have to read mass media publications to learn about new products. They changed the announcement date only because HD 4850 based products have already leaked into retail channel.

This actually ruined our review schedule. Alexey Berillo brought a sample from the event only on June 20 - the day this series was announced. With HD 4870 it was even worse: cards got stuck at the customs somewhere in Europe and were delivered to Russia already too late - only to be stuck at the local customs. What a pity. As you can see, that's not our bias in any way, that's just the way it is.

Anyway, HIS has kindly provided us with a sample of HD 4870, so we can finally publish our test results.

Graphics card

  • GPU: RADEON HD 4870 (RV770)
  • Interface: PCI-Express x16
  • GPU frequencies (ROPs/Shaders): 750/750 MHz (nominal - 750/750 MHz)
  • Memory frequencies (physical (effective)): 900 (3600) MHz (nominal - 900 (3600) MHz)
  • Memory bus width: 256bit
  • Vertex processors: -
  • Pixel processors: -
  • Unified processors: 800
  • Texture processors: 40 (BLF/TLF)
  • ROPs: 16
  • Dimensions: 220x100x33 mm (the last figure is maximum thickness of the graphics card).
  • PCB color: red
  • RAMDACs/TDMS: integrated into GPU.
  • Output connectors: 2xDVI (Dual-Link/HDMI), TV-out.
  • VIVO: not available
  • TV-out: integrated into GPU.
  • Multi-GPU operation: CrossFire (Hardware).


The card has 512 MB of GDDR5 SDRAM allocated in eight chips on the front side of the PCB.

Qimonda memory chips (GDDR5) designed for the maximum frequency of 1000 (4000) MHz.

Comparison with the reference design, front view
HIS RADEON HD 4870 512MB Reference ATI RADEON HD 4850 512MB

Comparison with the reference design, back view
HIS RADEON HD 4870 512MB Reference ATI RADEON HD 4850 512MB

Apparently, the 4850 and 4870 cards have conceptually similar designs, because they feature the same memory bus, the same core, they just operate at different frequencies. However, DDR5 memory used in the 4870 model and its higher power consumption than in the 4850 caused some differences in PCB layouts, especially in the power supply circuits.

By the way, circuit boards now have AMD logos.

What is it? The end of ATI? A gradual transition to AMD? The core however still bears the "ATI" logo.

The die was made on Week 23, that is in early June, 2008.

Graphics cards of this family are equipped with built-in audio codec. So this audio stream is then transmitted to HDMI (via a DVI-to-HDMI adapter). So if this function is important to you, make sure the bundle includes this adapter.

Also note that the graphics card uses two 6-pin power connectors. Unfortunately, they are placed at the end of the long PCB, which may cause some problems in case of less flexible, rigid cables.

The card has TV-Out with an original connector. You will need a special bundled adapter to output video to a TV set via S-Video or RCA.

Analog monitors with D-Sub (VGA) interface are connected with special DVI-to-D-Sub adapters. The bundle also includes DVI-to-HDMI adapters (these graphics cards support video/audio transfer to HDMI receivers), so there should be no problems with such monitors.

Maximum resolutions and frequencies:

  • 240 Hz max. refresh rate
  • 2048 x 1536 x 32bit x85Hz Max analog
  • 2560 x 1600 @ 60Hz Max digital (Dual-Link DVI)

What concerns MPEG2 playback features (DVD-Video), we analyzed this issue in 2002. Little has changed since that time. CPU load during video playback on modern graphics cards does not exceed 25%.

What concerns HDTV, a review is available here.

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Article navigation:

Page 1: Introduction, graphics card

Page 2: Cooling, bundle, package

Page 3: Performance in games

Page 4: Conclusions

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