Radeon HD 3870 X2 1GB vs Radeon HD 6790

Intro

Compare all that to the Radeon HD 6790, which comes with GPU core speed of 840 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also is made up of 800 Stream Processors, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 1GB should be a little 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 is much (more or less 27%) more effective 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 should be much (about 96%) better at anti-aliasing than the Radeon HD 6790, and 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: Bandwidth is the maximum amount of data (measured in megabytes per second) that can be moved across the external memory interface within a second. It's worked out by multiplying the interface width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka 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 - the lower the bandwidth is, the lower the ability to get to the max fill rate.