Radeon HD 3870 X2 1GB vs Radeon HD 7770

Intro

Compare those specifications to the Radeon HD 7770, which makes use of a 28 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 RAM runs at a frequency of 1125 MHz on this specific model. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB is 100% quicker than the Radeon HD 7770 in general, because of its higher bandwidth. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 72128 (100%)

Texel Rate

The Radeon HD 7770 is a lot (about 52%) better at AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 13600 (52%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 3870 X2 1GB is a better choice, by a large margin. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 7770		16000 Mpixels/sec
	Difference: 10400 (65%)

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 (in units of megabytes per second) that can be transferred past the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the 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 can be applied in one second. This number is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs 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 output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.