Radeon HD 3870 X2 512MB vs Radeon HD 4830 512MB

Intro

Compare those specifications to the Radeon HD 4830 512MB, which features a core clock speed of 575 MHz and a GDDR3 memory frequency of 900 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is made up of 640(128x5) SPUs, 32 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically, the Radeon HD 3870 X2 512MB should be quite a bit faster than the Radeon HD 4830 512MB in general. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4830 512MB		57600 MB/sec
	Difference: 57600 (100%)

Texel Rate

The Radeon HD 3870 X2 512MB will be a lot (about 43%) better at AF than the Radeon HD 4830 512MB. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4830 512MB		18400 Mtexels/sec
	Difference: 8000 (43%)

Pixel Rate

The Radeon HD 3870 X2 512MB should be much (about 187%) better at AA than the Radeon HD 4830 512MB, and able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 17200 (187%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be moved across the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's 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 number of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

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