GeForce GTX 275 vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which has a core clock speed of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also features a 384-bit bus, and uses a 28 nm design. It is made up of 2048 SPUs, 128 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 7990		375 Watts
	Difference: 156 Watts (71%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7990 should in theory be much better than the GeForce GTX 275 in general. (explain)

Radeon HD 7990		576000 MB/sec
GeForce GTX 275		127008 MB/sec
	Difference: 448992 (354%)

Texel Rate

The Radeon HD 7990 is a lot (more or less 380%) more effective at texture filtering than the GeForce GTX 275. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce GTX 275		50640 Mtexels/sec
	Difference: 192560 (380%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7990 is the winner, by a large margin. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce GTX 275		17724 Mpixels/sec
	Difference: 43076 (243%)

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 data (in units of MB per second) that can be transported over the external memory interface in a second. It is calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher 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 number of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.