Radeon HD 3870 X2 1GB vs Radeon HD 7990

Intro

Compare all that to the Radeon HD 7990, which comes with GPU core speed of 950 MHz, and 3072 MB of GDDR5 memory set to run at 1500 MHz through a 384-bit bus. It also is made up of 2048 Stream Processors, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7990, in theory, should be much faster than the Radeon HD 3870 X2 1GB in general. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 431872 (300%)

Texel Rate

The Radeon HD 7990 will be quite a bit (approximately 821%) faster with regards to anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 216800 (821%)

Pixel Rate

The Radeon HD 7990 is much (approximately 130%) better at anti-aliasing than the Radeon HD 3870 X2 1GB, and also capable of handling higher resolutions better. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 34400 (130%)

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 information (counted in MB per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the 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 amount of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

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