Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 650
IntroThe GeForce GT 640 DDR3 makes use of a 28 nm design. nVidia has clocked the core speed at 900 MHz. The DDR3 RAM works at a frequency of 1782 MHz on this specific model. It features 384 SPUs along with 32 TAUs and 16 ROPs.
Compare those specifications to the GeForce GTX 650, which has core speeds of 1058 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GTX 650 is 40% faster than the GeForce GT 640 DDR3 overall, because of its greater data rate. (explain)
Texel RateThe GeForce GTX 650 will be just a bit (more or less 18%) more effective at texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GTX 650 is a bit (approximately 18%) faster with regards to AA than the GeForce GT 640 DDR3, and also will be capable of handling higher 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.
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: Memory bandwidth is the max amount of data (measured in MB per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.