Radeon HD 3870 X2 1GB vs Radeon HD 6790

Intro

Compare those specs 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 memory. It features 800 SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 1GB should in theory be a small bit superior to the Radeon HD 6790 in general. (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 a lot (more or less 27%) faster with regards to 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 should be a lot (approximately 96%) better at AA than the Radeon HD 6790, and also will be able to handle higher 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 largest amount of data (measured in megabytes per second) that can be transferred across the external memory interface in a second. It is worked out by multiplying the card's 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 bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends 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.