Radeon HD 4870 X2 vs Radeon HD 7870 XT

Intro

Compare those specs to the Radeon HD 7870 XT, which features core speeds of 925 MHz on the GPU, and 1500 MHz on the 2048 MB of GDDR5 memory. It features 1536 SPUs as well as 96 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870 XT		185 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 165 Watts (89%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 X2 should theoretically be a little bit better than the Radeon HD 7870 XT in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7870 XT		192000 MB/sec
	Difference: 38400 (20%)

Texel Rate

The Radeon HD 7870 XT should be a lot (more or less 48%) better at anisotropic filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 7870 XT		88800 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 28800 (48%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7870 XT is the winner, by far. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 5600 (23%)

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 (in units of megabytes per second) that can be moved over the external memory interface within a second. The number is 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 card's memory bandwidth, the better 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 are applied in one second. This is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, 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 the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core 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 rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.