GeForce GTX 275 vs Radeon HD 6990

Intro

Compare that to the Radeon HD 6990, which has a clock frequency of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit memory bus, and uses a 40 nm design. It is made up 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 should be 152% quicker than the GeForce GTX 275 overall, because of 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 a lot (more or less 215%) more effective 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 is a lot (approximately 200%) more effective at FSAA than the GeForce GTX 275, and also should be capable of handling higher resolutions without slowing down too much. (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 max amount of information (counted in megabytes per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum 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 clock speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. 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 of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.