Radeon HD 4870 X2 vs Radeon HD 6750

Intro

Compare those specifications to the Radeon HD 6750, which comes with a clock frequency of 725 MHz and a GDDR5 memory speed of 1000 MHz. It also features a 128-bit memory bus, and makes use of a 40 nm design. It is comprised of 720 SPUs, 36 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750		86 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 264 Watts (307%)

Memory Bandwidth

The Radeon HD 4870 X2, in theory, should be a lot faster than the Radeon HD 6750 overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6750		64000 MB/sec
	Difference: 166400 (260%)

Texel Rate

The Radeon HD 4870 X2 is much (more or less 130%) more effective at texture filtering than the Radeon HD 6750. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6750		26100 Mtexels/sec
	Difference: 33900 (130%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 4870 X2 is a better choice, and very much so. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 6750		11600 Mpixels/sec
	Difference: 12400 (107%)

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 over the external memory interface in a second. It is worked out by multiplying the bus width by its memory clock speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

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