Radeon HD 3870 X2 512MB vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which comes with clock speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1280 SPUs along with 80 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 7870 will be 33% faster than the Radeon HD 3870 X2 512MB in general, due to its greater bandwidth. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 38400 (33%)

Texel Rate

The Radeon HD 7870 should be quite a bit (approximately 203%) more effective at anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 53600 (203%)

Pixel Rate

The Radeon HD 7870 will be a lot (approximately 21%) faster with regards to AA than the Radeon HD 3870 X2 512MB, and also will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 3870 X2 512MB		26400 Mpixels/sec
	Difference: 5600 (21%)

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 information (counted in megabytes per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If it uses 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 high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied in one second. This number is calculated by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the 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 the video card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.