Radeon HD 4870 X2 vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which makes use of a 28 nm design. AMD has clocked the core frequency at 1000 MHz. The GDDR5 RAM works at a frequency of 1200 MHz on this model. It features 1280 SPUs as well as 80 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 175 Watts (100%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be quite a bit faster than the Radeon HD 7870 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 7870		153600 MB/sec
	Difference: 76800 (50%)

Texel Rate

The Radeon HD 7870 is a lot (more or less 33%) more effective at texture filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 20000 (33%)

Pixel Rate

If using a high 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 4870 X2		24000 Mpixels/sec
	Difference: 8000 (33%)

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 maximum amount of data (in units of MB per second) that can be transported over the external memory interface in a second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. 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 is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.