Radeon HD 3870 X2 512MB vs Radeon HD 7870

Intro

Compare all of that 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 memory. It features 1280 SPUs as well as 80 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 is 33% quicker than the Radeon HD 3870 X2 512MB overall, because of its higher data rate. (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 (more or less 203%) faster with regards to 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

If running with a high screen resolution is important to you, then the Radeon HD 7870 is the winner, and very much so. (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: Bandwidth is the max amount of data (measured in MB per second) that can be transported past the external memory interface in one second. It's calculated by multiplying the bus width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total amount of texture units of the card 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 processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.