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Radeon HD 3870 X2 512MB vs Radeon HD 4850 2GB

Intro

The Radeon HD 3870 X2 512MB features a clock speed of 825 MHz and a GDDR3 memory speed of 900 MHz. It also features a 256-bit memory bus, and uses a 55 nm design. It is made up of 320(64x5) SPUs, 16 Texture Address Units, and 16 ROPs.

Compare all that to the Radeon HD 4850 2GB, which uses a 55 nm design. AMD has set the core frequency at 625 MHz. The GDDR4 memory works at a frequency of 993 MHz on this particular card. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 512MB should in theory be a lot superior to the Radeon HD 4850 2GB overall. (explain)

Radeon HD 3870 X2 512MB 115200 MB/sec
Radeon HD 4850 2GB 63552 MB/sec
Difference: 51648 (81%)

Texel Rate

The Radeon HD 3870 X2 512MB should be a little bit (more or less 6%) faster with regards to texture filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 3870 X2 512MB 26400 Mtexels/sec
Radeon HD 4850 2GB 25000 Mtexels/sec
Difference: 1400 (6%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be much (about 164%) more effective at anti-aliasing than the Radeon HD 4850 2GB, and also will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB 26400 Mpixels/sec
Radeon HD 4850 2GB 10000 Mpixels/sec
Difference: 16400 (164%)

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 512MB

Amazon.com

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Radeon HD 4850 2GB

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 512MB Radeon HD 4850 2GB
Manufacturer AMD AMD
Year Jan 28, 2008 Jun 25, 2008
Code Name R680 RV770 PRO
Memory 512 MB (x2) 2048 MB
Core Speed 825 MHz (x2) 625 MHz
Memory Speed 1800 MHz (x2) 1986 MHz
Power (Max TDP) (Unknown) watts 110 watts
Bandwidth 115200 MB/sec 63552 MB/sec
Texel Rate 26400 Mtexels/sec 25000 Mtexels/sec
Pixel Rate 26400 Mpixels/sec 10000 Mpixels/sec
Unified Shaders 320(64x5) (x2) 800(160x5)
Texture Mapping Units 16 (x2) 40
Render Output Units 16 (x2) 16
Bus Type GDDR3 GDDR4
Bus Width 256-bit (x2) 256-bit
Fab Process 55 nm 55 nm
Transistors (Unknown) million 956 million
Bus PCIe 2.0 x16/(internal PCIe 1.1 x16) PCIe 2.0 x16
DirectX Version DirectX 10.1 DirectX 10.1
OpenGL Version OpenGL 3.0 OpenGL 3.0

Memory Bandwidth: Memory bandwidth is the max amount of information (in units of MB per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

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

Display Prices

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Radeon HD 3870 X2 512MB

Amazon.com

Check prices at:

Radeon HD 4850 2GB

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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