Radeon HD 3870 X2 1GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which has a core clock speed of 840 MHz and a GDDR5 memory frequency of 1050 MHz. It also uses a 256-bit bus, and makes use of a 40 nm design. It features 800 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB should be 7% quicker than the Radeon HD 6790 overall, due to its higher bandwidth. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 6790		134400 MB/sec
	Difference: 9728 (7%)

Texel Rate

The Radeon HD 6790 should be much (more or less 27%) better at texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 7200 (27%)

Pixel Rate

The Radeon HD 3870 X2 1GB will be a lot (approximately 96%) more effective at FSAA than the Radeon HD 6790, and also capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 6790		13440 Mpixels/sec
	Difference: 12960 (96%)

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 max amount of information (in units of MB per second) that can be transported over the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the 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 number of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total number of texture units of the card by the core 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 processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.