GeForce GTX 580 3GB vs Radeon HD 6990

Intro

Compare that to the Radeon HD 6990, which has GPU clock speed of 830 MHz, and 2048 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also is comprised of 1536 Stream Processors, 96 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 580 3GB		244 Watts
Radeon HD 6990		375 Watts
	Difference: 131 Watts (54%)

Memory Bandwidth

The Radeon HD 6990 should theoretically be a lot faster than the GeForce GTX 580 3GB overall. (explain)

Radeon HD 6990		320000 MB/sec
GeForce GTX 580 3GB		192384 MB/sec
	Difference: 127616 (66%)

Texel Rate

The Radeon HD 6990 is quite a bit (more or less 223%) more effective at AF than the GeForce GTX 580 3GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce GTX 580 3GB		49408 Mtexels/sec
	Difference: 109952 (223%)

Pixel Rate

The Radeon HD 6990 is much (more or less 43%) more effective at AA than the GeForce GTX 580 3GB, and also will be able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce GTX 580 3GB		37056 Mpixels/sec
	Difference: 16064 (43%)

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 (in units of megabytes per second) that can be transferred past the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units by the core 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 in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.