Compare any two graphics cards:
Radeon HD 6950 2GB vs Radeon HD 7950 3GB
IntroThe Radeon HD 6950 2GB comes with clock speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1408 SPUs along with 88 Texture Address Units and 32 ROPs.
Compare all of that to the Radeon HD 7950 3GB, which makes use of a 28 nm design. AMD has clocked the core speed at 800 MHz. The GDDR5 memory runs at a frequency of 1250 MHz on this specific card. It features 1792 SPUs as well as 112 TAUs and 32 Rasterization Operator Units.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Performance-wise, the Radeon HD 7950 3GB should theoretically be much better than the Radeon HD 6950 2GB in general. (explain)
Texel RateThe Radeon HD 7950 3GB is a lot (approximately 27%) better at anisotropic filtering than the Radeon HD 6950 2GB. (explain)
Pixel RateBoth cards have the exact same pixel fill rate, so theoretically they should be equally good at at FSAA, and be capable of handling 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: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.