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Radeon HD 3870 512MB vs Radeon HD 4850 1GB

Intro

The Radeon HD 3870 512MB makes use of a 55 nm design. AMD has clocked the core frequency at 775 MHz. The GDDR3 memory works at a frequency of 900 MHz on this specific card. It features 320(64x5) SPUs as well as 16 TAUs and 16 ROPs.

Compare all that to the Radeon HD 4850 1GB, which has a core clock frequency of 625 MHz and a GDDR4 memory frequency of 993 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB 106 Watts
Radeon HD 4850 1GB 110 Watts
Difference: 4 Watts (4%)

Memory Bandwidth

In theory, the Radeon HD 4850 1GB will be 10% faster than the Radeon HD 3870 512MB in general, because of its greater bandwidth. (explain)

Radeon HD 4850 1GB 63552 MB/sec
Radeon HD 3870 512MB 57600 MB/sec
Difference: 5952 (10%)

Texel Rate

The Radeon HD 4850 1GB is a lot (approximately 102%) better at anisotropic filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4850 1GB 25000 Mtexels/sec
Radeon HD 3870 512MB 12400 Mtexels/sec
Difference: 12600 (102%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 3870 512MB is a better choice, and very much so. (explain)

Radeon HD 3870 512MB 12400 Mpixels/sec
Radeon HD 4850 1GB 10000 Mpixels/sec
Difference: 2400 (24%)

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 3870 512MB

Amazon.com

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Radeon HD 4850 1GB

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 512MB Radeon HD 4850 1GB
Manufacturer AMD AMD
Year Nov 19, 2007 Jun 25, 2008
Code Name RV670 XT RV770 PRO
Memory 512 MB 1024 MB
Core Speed 775 MHz 625 MHz
Memory Speed 1800 MHz 1986 MHz
Power (Max TDP) 106 watts 110 watts
Bandwidth 57600 MB/sec 63552 MB/sec
Texel Rate 12400 Mtexels/sec 25000 Mtexels/sec
Pixel Rate 12400 Mpixels/sec 10000 Mpixels/sec
Unified Shaders 320(64x5) 800(160x5)
Texture Mapping Units 16 40
Render Output Units 16 16
Bus Type GDDR3 GDDR4
Bus Width 256-bit 256-bit
Fab Process 55 nm 55 nm
Transistors (Unknown) million 956 million
Bus PCIe 2.0 x16/AGP 8x 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 maximum amount of data (in units of megabytes per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster 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 in one second. This figure is worked out by multiplying the total number of texture units 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 per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out 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 fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.

Display Prices

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Radeon HD 3870 512MB

Amazon.com

Check prices at:

Radeon HD 4850 1GB

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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