GeForce GTX 275 vs Radeon HD 6990

Intro

Compare all that to the Radeon HD 6990, which comes with GPU core speed of 830 MHz, and 2048 MB of GDDR5 RAM running at 1250 MHz through a 256-bit bus. It also is comprised of 1536 SPUs, 96 TAUs, and 32 ROPs.

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

In theory, the Radeon HD 6990 will be 152% quicker than the GeForce GTX 275 in general, due to its higher data rate. (explain)

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

Texel Rate

The Radeon HD 6990 is much (more or less 215%) better at texture 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 will be much (more or less 200%) better at full screen anti-aliasing than the GeForce GTX 275, and also should be capable of handling higher screen resolutions more effectively. (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 information (in units of MB per second) that can be transported across the external memory interface in one second. The number is calculated by multiplying the interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher 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 processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock 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 processed per second.

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