Compare any two graphics cards:
GeForce GT 340 1GB vs Radeon HD 4850 512MB
IntroThe GeForce GT 340 1GB uses a 40 nm design. nVidia has clocked the core speed at 550 MHz. The GDDR5 RAM works at a speed of 850 MHz on this card. It features 96 SPUs along with 32 Texture Address Units and 8 ROPs.
Compare those specs to the Radeon HD 4850 512MB, which makes use of a 55 nm design. AMD has set the core frequency at 625 MHz. The GDDR3 memory works at a frequency of 993 MHz on this particular card. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 4850 512MB should theoretically perform just a bit faster than the GeForce GT 340 1GB in general. (explain)
Texel RateThe Radeon HD 4850 512MB is a lot (more or less 42%) better at texture filtering than the GeForce GT 340 1GB. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the Radeon HD 4850 512MB is superior to the GeForce GT 340 1GB, 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: Memory bandwidth is the max amount of data (counted in MB per second) that can be moved over the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.