Compare any two graphics cards:
Radeon HD 6950 2GB vs Radeon HD 7950 3GB
IntroThe Radeon HD 6950 2GB has core speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1408 SPUs as well as 88 TAUs and 32 ROPs.
Compare those specs to the Radeon HD 7950 3GB, which has core speeds of 800 MHz on the GPU, and 1250 MHz on the 3072 MB of GDDR5 RAM. It features 1792 SPUs along with 112 TAUs and 32 Rasterization Operator Units.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
In theory, the Radeon HD 7950 3GB should be 50% faster than the Radeon HD 6950 2GB overall, because of its greater data rate. (explain)
Texel RateThe Radeon HD 7950 3GB should be a lot (about 27%) more effective at texture filtering than the Radeon HD 6950 2GB. (explain)
Pixel RateBoth cards have exactly the same pixel rate, so in theory they should be equally good at at full screen anti-aliasing, and be able to handle the same screen resolutions. (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.
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 (counted in megabytes per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 once 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 AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better the texel rate, the better the 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 amount of pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the clock speed of the card. 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 fill rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.