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Radeon HD 4890 1GB vs Radeon HD 6790

Intro

The Radeon HD 4890 1GB has a clock speed of 1000 MHz and a GDDR5 memory frequency of 975 MHz. It also makes use of a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Compare all that to the Radeon HD 6790, which comes with a core clock speed of 840 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 256-bit memory bus, and makes use of a 40 nm design. It is comprised of 800 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 6790 150 Watts
Radeon HD 4890 1GB 190 Watts
Difference: 40 Watts (27%)

Memory Bandwidth

The Radeon HD 6790 should in theory perform just a bit faster than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 6790 134400 MB/sec
Radeon HD 4890 1GB 124800 MB/sec
Difference: 9600 (8%)

Texel Rate

The Radeon HD 4890 1GB is a little bit (approximately 19%) better at texture filtering than the Radeon HD 6790. (explain)

Radeon HD 4890 1GB 40000 Mtexels/sec
Radeon HD 6790 33600 Mtexels/sec
Difference: 6400 (19%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4890 1GB is the winner, but it probably won't make a huge difference. (explain)

Radeon HD 4890 1GB 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 1GB

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 1GB Radeon HD 6790
Manufacturer AMD AMD
Year Apr 2, 2009 April 2011
Code Name RV790 XT Barts LE
Memory 1024 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 maximum amount of data (measured in megabytes per second) that can be moved past the external memory interface in a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics 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 amount of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka 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 memory bandwidth is, the lower the ability to reach the max fill rate.

Display Prices

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Radeon HD 4890 1GB

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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