Compare any two graphics cards:
GeForce 820M vs GeForce 8600 GT 256MB DDR2
IntroThe GeForce 820M features a clock frequency of 719 MHz and a DDR3 memory speed of 1000 MHz. It also makes use of a 64-bit memory bus, and uses a 28 nm design. It is comprised of 96 SPUs, 16 Texture Address Units, and 4 Raster Operation Units.
Compare those specs to the GeForce 8600 GT 256MB DDR2, which comes with clock speeds of 540 MHz on the GPU, and 400 MHz on the 256 MB of DDR2 RAM. It features 32 SPUs along with 16 Texture Address Units and 8 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce 820M should be 25% faster than the GeForce 8600 GT 256MB DDR2 overall, due to its greater data rate. (explain)
Texel RateThe GeForce 820M is a lot (approximately 33%) better at AF than the GeForce 8600 GT 256MB DDR2. (explain)
Pixel RateIf using a high screen resolution is important to you, then the GeForce 8600 GT 256MB DDR2 is a better choice, by a large margin. (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 (measured in megabytes per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster 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 texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total texture units of the card 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 per second.
Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units 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 output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.