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Radeon HD 4890 2GB vs Radeon HD 6790

Intro

The Radeon HD 4890 2GB uses a 55 nm design. AMD has clocked the core speed at 1000 MHz. The GDDR5 RAM is set to run at a speed of 975 MHz on this card. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Compare all of that to the Radeon HD 6790, which has core speeds of 840 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 800 SPUs as well as 40 Texture Address Units and 16 ROPs.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6790 150 Watts
Radeon HD 4890 2GB 190 Watts
Difference: 40 Watts (27%)

Memory Bandwidth

Performance-wise, the Radeon HD 6790 should theoretically be a small bit better than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 6790 134400 MB/sec
Radeon HD 4890 2GB 124800 MB/sec
Difference: 9600 (8%)

Texel Rate

The Radeon HD 4890 2GB is a small bit (approximately 19%) better at anisotropic filtering than the Radeon HD 6790. (explain)

Radeon HD 4890 2GB 40000 Mtexels/sec
Radeon HD 6790 33600 Mtexels/sec
Difference: 6400 (19%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 4890 2GB is superior to the Radeon HD 6790, not by a very large margin though. (explain)

Radeon HD 4890 2GB 16000 Mpixels/sec
Radeon HD 6790 13440 Mpixels/sec
Difference: 2560 (19%)

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 6790

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 6790
Manufacturer AMD AMD
Year Apr 2, 2009 April 2011
Code Name RV790 XT Barts LE
Memory 2048 MB 1024 MB
Core Speed 1000 MHz 840 MHz
Memory Speed 3900 MHz 4200 MHz
Power (Max TDP) 190 watts 150 watts
Bandwidth 124800 MB/sec 134400 MB/sec
Texel Rate 40000 Mtexels/sec 33600 Mtexels/sec
Pixel Rate 16000 Mpixels/sec 13440 Mpixels/sec
Unified Shaders 800(160x5) 800
Texture Mapping Units 40 40
Render Output Units 16 16
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 2.1 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 (counted in MB per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the interface width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is calculated by multiplying the total number of texture units of the card by the core clock 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 most pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.

Display Prices

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Radeon HD 4890 2GB

Amazon.com

Check prices at:

Radeon HD 6790

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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