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Radeon HD 3870 X2 1GB vs Radeon HD 6870

Intro

The Radeon HD 3870 X2 1GB comes with a GPU core clock speed of 825 MHz, and the 1024 MB of GDDR4 RAM runs at 1126 MHz through a 256-bit bus. It also features 320(64x5) SPUs, 16 TAUs, and 16 ROPs.

Compare that to the Radeon HD 6870, which comes with core clock speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 1120 SPUs as well as 56 Texture Address Units and 32 ROPs.

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 1GB should in theory perform a bit faster than the Radeon HD 6870 in general. (explain)

Radeon HD 3870 X2 1GB 144128 MB/sec
Radeon HD 6870 134400 MB/sec
Difference: 9728 (7%)

Texel Rate

The Radeon HD 6870 is a lot (about 91%) faster with regards to texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6870 50400 Mtexels/sec
Radeon HD 3870 X2 1GB 26400 Mtexels/sec
Difference: 24000 (91%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6870 is superior to the Radeon HD 3870 X2 1GB, though only just barely. (explain)

Radeon HD 6870 28800 Mpixels/sec
Radeon HD 3870 X2 1GB 26400 Mpixels/sec
Difference: 2400 (9%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

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Radeon HD 3870 X2 1GB

Amazon.com

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Radeon HD 6870

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 3870 X2 1GB Radeon HD 6870
Manufacturer AMD AMD
Year Jan 28, 2008 October 2010
Code Name R680 Barts XT
Memory 1024 MB (x2) 1024 MB
Core Speed 825 MHz (x2) 900 MHz
Memory Speed 2252 MHz (x2) 4200 MHz
Power (Max TDP) (Unknown) watts 151 watts
Bandwidth 144128 MB/sec 134400 MB/sec
Texel Rate 26400 Mtexels/sec 50400 Mtexels/sec
Pixel Rate 26400 Mpixels/sec 28800 Mpixels/sec
Unified Shaders 320(64x5) (x2) 1120
Texture Mapping Units 16 (x2) 56
Render Output Units 16 (x2) 32
Bus Type GDDR4 GDDR5
Bus Width 256-bit (x2) 256-bit
Fab Process 55 nm 40 nm
Transistors (Unknown) million 1700 million
Bus PCIe 2.0 x16/(internal PCIe 1.1 x16) PCIe x16
DirectX Version DirectX 10.1 DirectX 11
OpenGL Version OpenGL 3.0 OpenGL 4.1

Memory Bandwidth: Memory bandwidth is the largest amount of information (counted in MB per second) that can be transported past the external memory interface in one second. It is worked out by multiplying the bus width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.

Display Prices

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Radeon HD 3870 X2 1GB

Amazon.com

Check prices at:

Radeon HD 6870

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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