Compare any two graphics cards:
GeForce GTX 660 vs Radeon HD 6990
IntroThe GeForce GTX 660 has a GPU core speed of 980 MHz, and the 2048 MB of GDDR5 RAM runs at 1502 MHz through a 192-bit bus. It also is made up of 960 SPUs, 80 TAUs, and 24 ROPs.
Compare those specifications to the Radeon HD 6990, which has clock speeds of 830 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1536 SPUs as well as 96 TAUs and 32 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
As far as performance goes, the Radeon HD 6990 should theoretically be much superior to the GeForce GTX 660 overall. (explain)
Texel RateThe Radeon HD 6990 should be much (approximately 103%) faster with regards to anisotropic filtering than the GeForce GTX 660. (explain)
Pixel RateIf running with high levels of AA is important to you, then the Radeon HD 6990 is superior to the GeForce GTX 660, by a large margin. (explain)
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 ComparisonPlease note that the price comparisons are based on search keywords, and might not be the exact same card listed on this page. We have no control over the accuracy of their search results.
Memory Bandwidth: Bandwidth is the maximum amount of data (measured in megabytes per second) that can be moved over the external memory interface in one second. It is calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics 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 most pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.