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Radeon HD 4870 2GB vs Radeon HD 4890 1GB

Intro

The Radeon HD 4870 2GB features a GPU core clock speed of 750 MHz, and the 2048 MB of GDDR5 RAM is set to run at 900 MHz through a 256-bit bus. It also is made up of 800(160x5) Stream Processors, 40 TAUs, and 16 ROPs.

Compare that to the Radeon HD 4890 1GB, which has GPU clock speed of 1000 MHz, and 1024 MB of GDDR5 memory set to run at 975 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB 150 Watts
Radeon HD 4890 1GB 190 Watts
Difference: 40 Watts (27%)

Memory Bandwidth

Performance-wise, the Radeon HD 4890 1GB should theoretically be just a bit superior to the Radeon HD 4870 2GB overall. (explain)

Radeon HD 4890 1GB 124800 MB/sec
Radeon HD 4870 2GB 115200 MB/sec
Difference: 9600 (8%)

Texel Rate

The Radeon HD 4890 1GB will be much (about 33%) better at AF than the Radeon HD 4870 2GB. (explain)

Radeon HD 4890 1GB 40000 Mtexels/sec
Radeon HD 4870 2GB 30000 Mtexels/sec
Difference: 10000 (33%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 4890 1GB is the winner, and very much so. (explain)

Radeon HD 4890 1GB 16000 Mpixels/sec
Radeon HD 4870 2GB 12000 Mpixels/sec
Difference: 4000 (33%)

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 4870 2GB

Amazon.com

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Radeon HD 4890 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 4870 2GB Radeon HD 4890 1GB
Manufacturer AMD AMD
Year Jun 25, 2008 Apr 2, 2009
Code Name RV770 XT RV790 XT
Memory 2048 MB 1024 MB
Core Speed 750 MHz 1000 MHz
Memory Speed 3600 MHz 3900 MHz
Power (Max TDP) 150 watts 190 watts
Bandwidth 115200 MB/sec 124800 MB/sec
Texel Rate 30000 Mtexels/sec 40000 Mtexels/sec
Pixel Rate 12000 Mpixels/sec 16000 Mpixels/sec
Unified Shaders 800(160x5) 800(160x5)
Texture Mapping Units 40 40
Render Output Units 16 16
Bus Type GDDR5 GDDR5
Bus Width 256-bit 256-bit
Fab Process 55 nm 55 nm
Transistors 956 million 959 million
Bus PCIe 2.0 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 data (measured in MB per second) that can be transported past the external memory interface in a second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one 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 video 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 most pixels that the graphics chip can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.

Display Prices

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Radeon HD 4870 2GB

Amazon.com

Check prices at:

Radeon HD 4890 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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