Radeon HD 4870 X2 vs Radeon HD 6750 1GB

Intro

Compare those specifications to the Radeon HD 6750 1GB, which has a core clock speed of 725 MHz and a GDDR5 memory frequency of 1000 MHz. It also makes use of a 128-bit bus, and makes use of a 40 nm design. It features 720 SPUs, 36 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750 1GB		86 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 264 Watts (307%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 should be 260% quicker than the Radeon HD 6750 1GB overall, due to its higher data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6750 1GB		64000 MB/sec
	Difference: 166400 (260%)

Texel Rate

The Radeon HD 4870 X2 should be a lot (about 130%) faster with regards to AF than the Radeon HD 6750 1GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6750 1GB		26100 Mtexels/sec
	Difference: 33900 (130%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4870 X2 is the winner, by a large margin. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 6750 1GB		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 maximum amount of information (counted in MB per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the card's interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The higher the texel rate, the better the video 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 the video card could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called 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 potential to get to the max fill rate.