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Radeon HD 4890 2GB vs Radeon HD 6870

Intro

The Radeon HD 4890 2GB features a clock speed of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Compare that to the Radeon HD 6870, which has a GPU core clock speed of 900 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also is made up of 1120 SPUs, 56 TAUs, and 32 Raster Operation Units.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870 151 Watts
Radeon HD 4890 2GB 190 Watts
Difference: 39 Watts (26%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6870 should perform just a bit faster than the Radeon HD 4890 2GB overall. (explain)

Radeon HD 6870 134400 MB/sec
Radeon HD 4890 2GB 124800 MB/sec
Difference: 9600 (8%)

Texel Rate

The Radeon HD 6870 is a lot (approximately 26%) better at texture filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 6870 50400 Mtexels/sec
Radeon HD 4890 2GB 40000 Mtexels/sec
Difference: 10400 (26%)

Pixel Rate

The Radeon HD 6870 should be a lot (approximately 80%) more effective at anti-aliasing than the Radeon HD 4890 2GB, and also will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 6870 28800 Mpixels/sec
Radeon HD 4890 2GB 16000 Mpixels/sec
Difference: 12800 (80%)

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 4890 2GB

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 4890 2GB Radeon HD 6870
Manufacturer AMD AMD
Year Apr 2, 2009 October 2010
Code Name RV790 XT Barts XT
Memory 2048 MB 1024 MB
Core Speed 1000 MHz 900 MHz
Memory Speed 3900 MHz 4200 MHz
Power (Max TDP) 190 watts 151 watts
Bandwidth 124800 MB/sec 134400 MB/sec
Texel Rate 40000 Mtexels/sec 50400 Mtexels/sec
Pixel Rate 16000 Mpixels/sec 28800 Mpixels/sec
Unified Shaders 800(160x5) 1120
Texture Mapping Units 40 56
Render Output Units 16 32
Bus Type GDDR5 GDDR5
Bus Width 256-bit 256-bit
Fab Process 55 nm 40 nm
Transistors 959 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 data (in units of megabytes per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, 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 amount of texture map elements (texels) that are processed per second. This is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core 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 output rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.

Display Prices

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Radeon HD 4890 2GB

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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