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Radeon HD 3870 X2 1GB vs Radeon HD 6850

Intro

The Radeon HD 3870 X2 1GB comes with core speeds of 825 MHz on the GPU, and 1126 MHz on the 1024 MB of GDDR4 memory. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 Rasterization Operator Units.

Compare all that to the Radeon HD 6850, which features a core clock frequency of 775 MHz and a GDDR5 memory speed of 1000 MHz. It also features a 256-bit bus, and uses a 40 nm design. It features 960 SPUs, 48 TAUs, and 32 ROPs.

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB should perform a bit faster than the Radeon HD 6850 overall. (explain)

Radeon HD 3870 X2 1GB 144128 MB/sec
Radeon HD 6850 128000 MB/sec
Difference: 16128 (13%)

Texel Rate

The Radeon HD 6850 should be much (about 41%) faster with regards to anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6850 37200 Mtexels/sec
Radeon HD 3870 X2 1GB 26400 Mtexels/sec
Difference: 10800 (41%)

Pixel Rate

The Radeon HD 3870 X2 1GB should be just a bit (approximately 6%) faster with regards to anti-aliasing than the Radeon HD 6850, and able to handle higher resolutions while still performing well. (explain)

Radeon HD 3870 X2 1GB 26400 Mpixels/sec
Radeon HD 6850 24800 Mpixels/sec
Difference: 1600 (6%)

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 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 3870 X2 1GB Radeon HD 6850
Manufacturer AMD AMD
Year Jan 28, 2008 October 2010
Code Name R680 Barts Pro
Memory 1024 MB (x2) 1024 MB
Core Speed 825 MHz (x2) 775 MHz
Memory Speed 2252 MHz (x2) 4000 MHz
Power (Max TDP) (Unknown) watts 127 watts
Bandwidth 144128 MB/sec 128000 MB/sec
Texel Rate 26400 Mtexels/sec 37200 Mtexels/sec
Pixel Rate 26400 Mpixels/sec 24800 Mpixels/sec
Unified Shaders 320(64x5) (x2) 960
Texture Mapping Units 16 (x2) 48
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 max amount of data (counted in megabytes per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the interface width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the 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 amount of texture map elements (texels) that can be processed per second. This is worked out by multiplying the total texture units of the card by the core 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 most pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.

Display Prices

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Radeon HD 3870 X2 1GB

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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