Radeon HD 3870 X2 1GB vs Radeon HD 6790

Intro

Compare that to the Radeon HD 6790, which makes use of a 40 nm design. AMD has clocked the core speed at 840 MHz. The GDDR5 memory works at a frequency of 1050 MHz on this specific card. It features 800 SPUs as well as 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 should perform 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 will be a lot (approximately 27%) more effective at anisotropic 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 quite a bit (approximately 96%) better at anti-aliasing than the Radeon HD 6790, and also will be capable of handling higher screen resolutions more effectively. (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 largest amount of data (in units of megabytes per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the bus width by the speed of its memory. If it uses DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is calculated by multiplying the total amount of texture units by the core speed of the chip. The better 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 maximum amount of pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.