Radeon HD 3870 512MB vs Radeon HD 4830 512MB

Intro

Compare all of that to the Radeon HD 4830 512MB, which has a GPU core clock speed of 575 MHz, and 512 MB of GDDR3 RAM running at 900 MHz through a 256-bit bus. It also features 640(128x5) Stream Processors, 32 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 512MB		95 Watts
Radeon HD 3870 512MB		106 Watts
	Difference: 11 Watts (12%)

Memory Bandwidth

Both cards have the exact same memory bandwidth, so theoretically they should perform exactly the same. (explain)

Texel Rate

The Radeon HD 4830 512MB will be quite a bit (more or less 48%) faster with regards to anisotropic filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 4830 512MB		18400 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 6000 (48%)

Pixel Rate

The Radeon HD 3870 512MB should be quite a bit (approximately 35%) more effective at full screen anti-aliasing than the Radeon HD 4830 512MB, and also able to handle higher screen resolutions better. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 3200 (35%)

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 max amount of data (counted in MB per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units 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 one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated 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 drawing the pixels (image) on 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 potential to reach the max fill rate.