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Radeon HD 4870 2GB vs Radeon HD 6850

Intro

The Radeon HD 4870 2GB uses a 55 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 memory works at a frequency of 900 MHz on this model. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

Compare those specs to the Radeon HD 6850, which comes with GPU clock speed of 775 MHz, and 1024 MB of GDDR5 RAM set to run at 1000 MHz through a 256-bit bus. It also features 960 Stream Processors, 48 TAUs, and 32 ROPs.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850 127 Watts
Radeon HD 4870 2GB 150 Watts
Difference: 23 Watts (18%)

Memory Bandwidth

Performance-wise, the Radeon HD 6850 should in theory be just a bit better than the Radeon HD 4870 2GB in general. (explain)

Radeon HD 6850 128000 MB/sec
Radeon HD 4870 2GB 115200 MB/sec
Difference: 12800 (11%)

Texel Rate

The Radeon HD 6850 should be a lot (more or less 24%) faster with regards to anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6850 37200 Mtexels/sec
Radeon HD 4870 2GB 30000 Mtexels/sec
Difference: 7200 (24%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4870 2GB, and very much so. (explain)

Radeon HD 6850 24800 Mpixels/sec
Radeon HD 4870 2GB 12000 Mpixels/sec
Difference: 12800 (107%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

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Radeon HD 4870 2GB

Amazon.com

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Radeon HD 6850

Amazon.com

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Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

Specifications

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Model Radeon HD 4870 2GB Radeon HD 6850
Manufacturer AMD AMD
Year Jun 25, 2008 October 2010
Code Name RV770 XT Barts Pro
Memory 2048 MB 1024 MB
Core Speed 750 MHz 775 MHz
Memory Speed 3600 MHz 4000 MHz
Power (Max TDP) 150 watts 127 watts
Bandwidth 115200 MB/sec 128000 MB/sec
Texel Rate 30000 Mtexels/sec 37200 Mtexels/sec
Pixel Rate 12000 Mpixels/sec 24800 Mpixels/sec
Unified Shaders 800(160x5) 960
Texture Mapping Units 40 48
Render Output Units 16 32
Bus Type GDDR5 GDDR5
Bus Width 256-bit 256-bit
Fab Process 55 nm 40 nm
Transistors 956 million 1700 million
Bus PCIe 2.0 x16 PCIe x16
DirectX Version DirectX 10.1 DirectX 11
OpenGL Version OpenGL 3.0 OpenGL 4.1

Memory Bandwidth: Bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in one second. The number is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.

Display Prices

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Radeon HD 4870 2GB

Amazon.com

Check prices at:

Radeon HD 6850

Amazon.com

Check prices at:

Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

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