Compare any two graphics cards:
GeForce GT 640 DDR3 vs Radeon HD 5850
IntroThe GeForce GT 640 DDR3 comes with a GPU core speed of 900 MHz, and the 2048 MB of DDR3 RAM is set to run at 1782 MHz through a 128-bit bus. It also features 384 Stream Processors, 32 TAUs, and 16 Raster Operation Units.
Compare those specs to the Radeon HD 5850, which uses a 40 nm design. AMD has clocked the core speed at 725 MHz. The GDDR5 RAM runs at a frequency of 1000 MHz on this card. It features 1440(288x5) SPUs as well as 72 Texture Address Units and 32 Rasterization Operator Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the Radeon HD 5850 should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe Radeon HD 5850 is much (more or less 81%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf using a high resolution is important to you, then the Radeon HD 5850 is a better choice, and very much so. (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: Bandwidth is the maximum amount of information (in units of megabytes per second) that can be transferred over the external memory interface in a second. The number is worked out by multiplying the card's interface width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 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 high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.