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Radeon HD 4790 vs Radeon HD 4870 2GB

Intro

The Radeon HD 4790 uses a 55 nm design. AMD has set the core frequency at 600 MHz. The GDDR5 RAM works at a speed of 800 MHz on this particular model. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.

Compare those specs to the Radeon HD 4870 2GB, which uses a 55 nm design. AMD has set the core frequency at 750 MHz. The GDDR5 memory works at a frequency of 900 MHz on this particular card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4870 2GB should in theory perform a small bit faster than the Radeon HD 4790 in general. (explain)

Radeon HD 4870 2GB 115200 MB/sec
Radeon HD 4790 102400 MB/sec
Difference: 12800 (13%)

Texel Rate

The Radeon HD 4870 2GB should be much (approximately 56%) more effective at anisotropic filtering than the Radeon HD 4790. (explain)

Radeon HD 4870 2GB 30000 Mtexels/sec
Radeon HD 4790 19200 Mtexels/sec
Difference: 10800 (56%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 4870 2GB is superior to the Radeon HD 4790, by far. (explain)

Radeon HD 4870 2GB 12000 Mpixels/sec
Radeon HD 4790 9600 Mpixels/sec
Difference: 2400 (25%)

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 4790

Amazon.com

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Radeon HD 4870 2GB

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 4790 Radeon HD 4870 2GB
Manufacturer AMD AMD
Year 2009 Jun 25, 2008
Code Name RV790 RV770 XT
Memory 512 MB 2048 MB
Core Speed 600 MHz 750 MHz
Memory Speed 3200 MHz 3600 MHz
Power (Max TDP) (Unknown) watts 150 watts
Bandwidth 102400 MB/sec 115200 MB/sec
Texel Rate 19200 Mtexels/sec 30000 Mtexels/sec
Pixel Rate 9600 Mpixels/sec 12000 Mpixels/sec
Unified Shaders 640(128x5) 800(160x5)
Texture Mapping Units 32 40
Render Output Units 16 16
Bus Type GDDR5 GDDR5
Bus Width 256-bit 256-bit
Fab Process 55 nm 55 nm
Transistors 959 million 956 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 maximum amount of information (measured in megabytes per second) that can be transported across the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. In the case of 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 anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.

Display Prices

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Radeon HD 4790

Amazon.com

Check prices at:

Radeon HD 4870 2GB

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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