Compare any two graphics cards:
GeForce GT 340 vs Radeon HD 4850 X2 1GB
IntroThe GeForce GT 340 comes with a clock speed of 550 MHz and a GDDR5 memory speed of 850 MHz. It also uses a 128-bit memory bus, and uses a 40 nm design. It features 96 SPUs, 32 Texture Address Units, and 8 ROPs.
Compare that to the Radeon HD 4850 X2 1GB, which has core clock speeds of 625 MHz on the GPU, and 993 MHz on the 1024 MB of GDDR3 memory. It features 800(160x5) SPUs as well as 40 TAUs and 16 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 4850 X2 1GB should perform quite a bit faster than the GeForce GT 340 overall. (explain)
Texel RateThe Radeon HD 4850 X2 1GB should be much (approximately 184%) more effective at texture filtering than the GeForce GT 340. (explain)
Pixel RateThe Radeon HD 4850 X2 1GB should be quite a bit (more or less 355%) faster with regards to anti-aliasing than the GeForce GT 340, and capable of handling higher screen resolutions better. (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.
Memory Bandwidth: Bandwidth is the max amount of information (counted in MB per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the interface width by its memory speed. If it uses DDR memory, 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, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied 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 processed in a second.
Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated 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 drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.