Compare any two graphics cards:
GeForce 9800 GT 1GB vs GeForce GT 640 DDR3
IntroThe GeForce 9800 GT 1GB has a GPU core clock speed of 600 MHz, and the 1024 MB of GDDR3 RAM is set to run at 900 MHz through a 256-bit bus. It also is made up of 112 Stream Processors, 56 Texture Address Units, and 16 Raster Operation Units.
Compare all that to the GeForce GT 640 DDR3, which has GPU clock speed of 900 MHz, and 2048 MB of DDR3 RAM set to run at 1782 MHz through a 128-bit bus. It also features 384 Stream Processors, 32 Texture Address Units, and 16 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce 9800 GT 1GB should in theory be a small bit superior to the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce 9800 GT 1GB is a little bit (about 17%) more effective at AF than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GT 640 DDR3 is much (approximately 50%) more effective at anti-aliasing than the GeForce 9800 GT 1GB, and will be capable of handling higher screen 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: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, 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 number of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.