Radeon HD 3870 X2 1GB vs Radeon HD 6770

Intro

Compare all that to the Radeon HD 6770, which comes with a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 128-bit memory bus, and uses a 40 nm design. It is made up of 800 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 1GB should theoretically be a lot superior to the Radeon HD 6770 in general. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 76928 (114%)

Texel Rate

The Radeon HD 6770 should be much (about 36%) more effective at anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6770		36000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 9600 (36%)

Pixel Rate

The Radeon HD 3870 X2 1GB is a lot (about 83%) more effective at FSAA than the Radeon HD 6770, and also will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 6770		14400 Mpixels/sec
	Difference: 12000 (83%)

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 information (measured in megabytes per second) that can be transferred over the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.