Radeon HD 3870 X2 1GB vs Radeon HD 7970

Intro

Compare all of that to the Radeon HD 7970, which features GPU clock speed of 925 MHz, and 3072 MB of GDDR5 RAM set to run at 1375 MHz through a 384-bit bus. It also is made up of 2048 SPUs, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7970, in theory, should perform much faster than the Radeon HD 3870 X2 1GB in general. (explain)

Radeon HD 7970		264000 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 119872 (83%)

Texel Rate

The Radeon HD 7970 will be quite a bit (approximately 348%) more effective at anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 7970		118400 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 92000 (348%)

Pixel Rate

The Radeon HD 7970 will be just a bit (approximately 12%) better at full screen anti-aliasing than the Radeon HD 3870 X2 1GB, and also should be able to handle higher resolutions better. (explain)

Radeon HD 7970		29600 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 3200 (12%)

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 largest amount of information (measured in MB per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.