Radeon HD 3870 X2 1GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which comes with clock speeds of 840 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 RAM. It features 800 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 1GB, in theory, should be a small bit faster than the Radeon HD 6790 overall. (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 quite a bit (about 27%) more effective at AF 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

If using high levels of AA is important to you, then the Radeon HD 3870 X2 1GB is a better choice, and very much so. (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 maximum amount of data (measured in megabytes per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the card's interface width by its memory speed. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

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