Radeon HD 4870 X2 vs Radeon HD 6770

Intro

Compare those specifications to the Radeon HD 6770, which features a GPU core clock speed of 900 MHz, and 512 MB of GDDR5 RAM running at 1050 MHz through a 128-bit bus. It also features 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770		108 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 242 Watts (224%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be 243% faster than the Radeon HD 6770 in general, due to its greater bandwidth. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 163200 (243%)

Texel Rate

The Radeon HD 4870 X2 is much (more or less 67%) better at AF than the Radeon HD 6770. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6770		36000 Mtexels/sec
	Difference: 24000 (67%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4870 X2 is a better choice, by far. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 6770		14400 Mpixels/sec
	Difference: 9600 (67%)

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 information (in units of MB per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher 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 amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.