Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 550 Ti
IntroThe GeForce GT 640 DDR3 features core 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 all of that to the GeForce GTX 550 Ti, which features core clock speeds of 900 MHz on the GPU, and 1026 MHz on the 1024 MB of GDDR5 RAM. It features 192 SPUs along with 32 Texture Address Units and 24 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 550 Ti should theoretically perform quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateBoth cards have the exact same texel fill rate, so in theory they should perform equally good at at anisotropic filtering. (explain)
Pixel RateThe GeForce GTX 550 Ti is much (more or less 50%) faster with regards to full screen anti-aliasing than the GeForce GT 640 DDR3, and will be capable of handling higher screen resolutions more effectively. (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 largest amount of data (measured in MB per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the bus width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.