Compare any two graphics cards:
Geforce GTX 770 vs Radeon HD 7990
IntroThe Geforce GTX 770 comes with a GPU core speed of 1046 MHz, and the 2048 MB of GDDR5 memory runs at 1753 MHz through a 256-bit bus. It also is comprised of 1536 Stream Processors, 128 Texture Address Units, and 32 ROPs.
Compare that to the Radeon HD 7990, which uses a 28 nm design. AMD has clocked the core speed at 950 MHz. The GDDR5 RAM works at a speed of 1500 MHz on this model. It features 2048 SPUs as well as 128 TAUs and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 7990 is 157% faster than the Geforce GTX 770 overall, due to its higher bandwidth. (explain)
Texel RateThe Radeon HD 7990 is much (about 82%) more effective at AF than the Geforce GTX 770. (explain)
Pixel RateThe Radeon HD 7990 will be quite a bit (approximately 82%) faster with regards to FSAA than the Geforce GTX 770, and also will be able to handle higher resolutions while still performing well. (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.
Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.
Memory Bandwidth: Bandwidth is the max amount of information (in units of megabytes per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, 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 number is calculated by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called 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, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.