Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 650
IntroThe GeForce GT 640 DDR3 comes with clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.
Compare those specs to the GeForce GTX 650, which features GPU core speed of 1058 MHz, and 2048 MB of GDDR5 memory set to run at 1250 MHz through a 128-bit bus. It also features 384 Stream Processors, 32 TAUs, and 16 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce GTX 650 should theoretically be quite a bit superior to the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 650 should be just a bit (more or less 18%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with high levels of AA is important to you, then the GeForce GTX 650 is the winner, though not 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.
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 max amount of data (counted in megabytes per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is worked out by multiplying the total number of 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.
Pixel Rate: Pixel rate is the most pixels the video card can 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 Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.