Compare any two graphics cards:
GeForce GTX 580 3GB vs Radeon HD 6950
IntroThe GeForce GTX 580 3GB makes use of a 40 nm design. nVidia has clocked the core speed at 772 MHz. The GDDR5 memory is set to run at a speed of 1002 MHz on this card. It features 512 SPUs as well as 64 TAUs and 48 ROPs.
Compare all of that to the Radeon HD 6950, which makes use of a 40 nm design. AMD has clocked the core frequency at 800 MHz. The GDDR5 RAM works at a frequency of 1250 MHz on this model. It features 1408 SPUs as well as 88 Texture Address Units and 32 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce GTX 580 3GB should in theory be a small bit superior to the Radeon HD 6950 in general. (explain)
Texel RateThe Radeon HD 6950 is much (approximately 42%) more effective at AF than the GeForce GTX 580 3GB. (explain)
Pixel RateIf using a high resolution is important to you, then the GeForce GTX 580 3GB is superior to the Radeon HD 6950, by far. (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.
Memory Bandwidth: Bandwidth is the largest amount of data (counted in megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 processed 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 this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.