Radeon HD 3870 512MB vs Radeon HD 4730

Intro

Compare those specs to the Radeon HD 4730, which comes with GPU clock speed of 700 MHz, and 512 MB of GDDR5 memory running at 900 MHz through a 128-bit bus. It also features 640(128x5) SPUs, 32 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
Radeon HD 4730		140 Watts
	Difference: 34 Watts (32%)

Memory Bandwidth

Both cards have exactly the same bandwidth, so in theory they should perform exactly the same. (explain)

Texel Rate

The Radeon HD 4730 is quite a bit (approximately 81%) better at anisotropic filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4730		22400 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 10000 (81%)

Pixel Rate

The Radeon HD 3870 512MB should be quite a bit (about 121%) faster with regards to full screen anti-aliasing than the Radeon HD 4730, and also able to handle higher screen resolutions more effectively. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4730		5600 Mpixels/sec
	Difference: 6800 (121%)

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

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (counted in MB per second) that can be transported past the external memory interface in a second. The number is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, 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 amount of texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.