Compare any two graphics cards:
GeForce GT 640 DDR3 vs Radeon HD 4850 2GB
IntroThe GeForce GT 640 DDR3 has a core clock frequency of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also makes use of a 128-bit bus, and makes use of a 28 nm design. It is comprised of 384 SPUs, 32 TAUs, and 16 Raster Operation Units.
Compare those specs to the Radeon HD 4850 2GB, which has GPU clock speed of 625 MHz, and 2048 MB of GDDR4 memory running at 993 MHz through a 256-bit bus. It also is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 4850 2GB should in theory be a bit faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GT 640 DDR3 should be a small bit (about 15%) more effective at AF than the Radeon HD 4850 2GB. (explain)
Pixel RateIf using a high screen resolution is important to you, then the GeForce GT 640 DDR3 is the winner, and very much so. (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 information (in units of MB per second) that can be transported over the external memory interface in a second. The number is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total number of 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 amount of pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.