Radeon HD 4850 X2 512MB vs Radeon HD 6770

Intro

Compare those specs to the Radeon HD 6770, which makes use of a 40 nm design. AMD has set the core frequency at 900 MHz. The GDDR5 memory is set to run at a frequency of 1050 MHz on this model. It features 800 SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770		108 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 142 Watts (131%)

Memory Bandwidth

Theoretically, the Radeon HD 4850 X2 512MB should perform much faster than the Radeon HD 6770 in general. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 59904 (89%)

Texel Rate

The Radeon HD 4850 X2 512MB will be much (more or less 39%) better at anisotropic filtering than the Radeon HD 6770. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 6770		36000 Mtexels/sec
	Difference: 14000 (39%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 4850 X2 512MB is the winner, by a large margin. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 6770		14400 Mpixels/sec
	Difference: 5600 (39%)

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 largest amount of data (counted in MB per second) that can be moved over the external memory interface within a second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics 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 maximum number of pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.