Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 650 Ti 2GB
IntroThe GeForce GT 640 DDR3 comes with a GPU core speed of 900 MHz, and the 2048 MB of DDR3 memory runs at 1782 MHz through a 128-bit bus. It also is comprised of 384 Stream Processors, 32 Texture Address Units, and 16 Raster Operation Units.
Compare that to the GeForce GTX 650 Ti 2GB, which uses a 28 nm design. nVidia has clocked the core speed at 928 MHz. The GDDR5 RAM works at a frequency of 1350 MHz on this particular model. It features 768 SPUs as well as 64 Texture Address Units and 16 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 650 Ti 2GB should be quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 650 Ti 2GB should be a lot (approximately 106%) better at AF than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GTX 650 Ti 2GB is a bit (more or less 3%) faster with regards to AA than the GeForce GT 640 DDR3, and able to handle higher resolutions without losing too much performance. (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 transported past the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, 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 number of pixels that the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs 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 fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.