GeForce GTX 275 vs Radeon HD 6990

Intro

Compare all that to the Radeon HD 6990, which has a clock frequency of 830 MHz and a GDDR5 memory frequency of 1250 MHz. It also uses a 256-bit bus, and uses a 40 nm design. It features 1536 SPUs, 96 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 275		219 Watts
Radeon HD 6990		375 Watts
	Difference: 156 Watts (71%)

Memory Bandwidth

The Radeon HD 6990 should theoretically perform quite a bit faster than the GeForce GTX 275 overall. (explain)

Radeon HD 6990		320000 MB/sec
GeForce GTX 275		127008 MB/sec
	Difference: 192992 (152%)

Texel Rate

The Radeon HD 6990 will be quite a bit (more or less 215%) faster with regards to anisotropic filtering than the GeForce GTX 275. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce GTX 275		50640 Mtexels/sec
	Difference: 108720 (215%)

Pixel Rate

The Radeon HD 6990 should be much (more or less 200%) faster with regards to anti-aliasing than the GeForce GTX 275, and also should be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce GTX 275		17724 Mpixels/sec
	Difference: 35396 (200%)

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 (measured in MB per second) that can be transported past the external memory interface in one second. It's calculated by multiplying the card's bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units 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 lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.