Compare any two graphics cards:
GeForce 9800 GT 1GB vs GeForce GT 640 DDR3
IntroThe GeForce 9800 GT 1GB uses a 65/55 nm design. nVidia has set the core frequency at 600 MHz. The GDDR3 memory runs at a speed of 900 MHz on this card. It features 112 SPUs as well as 56 TAUs and 16 ROPs.
Compare those specifications to the GeForce GT 640 DDR3, which has core speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce 9800 GT 1GB should theoretically be just a bit superior to the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce 9800 GT 1GB will be a bit (more or less 17%) better at anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GT 640 DDR3 will be a lot (approximately 50%) faster with regards to FSAA than the GeForce 9800 GT 1GB, and also will be able to handle higher resolutions without slowing down too much. (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 largest amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.
Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.