Compare any two graphics cards:
Radeon HD 4850 2GB vs Radeon HD 4850 X2 1GB
IntroThe Radeon HD 4850 2GB uses a 55 nm design. AMD has clocked the core frequency at 625 MHz. The GDDR4 memory works at a speed of 993 MHz on this particular model. It features 800(160x5) SPUs as well as 40 TAUs and 16 ROPs.
Compare all that to the Radeon HD 4850 X2 1GB, which makes use of a 55 nm design. AMD has clocked the core frequency at 625 MHz. The GDDR3 memory works at a speed of 993 MHz on this model. 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 will be 100% faster than the Radeon HD 4850 2GB overall, due to its higher data rate. (explain)
Texel RateThe Radeon HD 4850 X2 1GB is quite a bit (more or less 100%) better at texture filtering than the Radeon HD 4850 2GB. (explain)
Pixel RateIf using a high resolution is important to you, then the Radeon HD 4850 X2 1GB is superior to the Radeon HD 4850 2GB, by a large margin. (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.
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 largest amount of information (counted in MB per second) that can be moved past the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR type memory, the result should 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 anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. The figure 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 output rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.