GeForce 820M vs GeForce 8800 GTS (G80) 640MB

Intro

Compare those specifications to the GeForce 8800 GTS (G80) 640MB, which has core clock speeds of 513 MHz on the GPU, and 792 MHz on the 640 MB of GDDR3 RAM. It features 96 SPUs along with 48 TAUs and 20 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 8800 GTS (G80) 640MB		143 Watts
	Difference: 128 Watts (853%)

Memory Bandwidth

In theory, the GeForce 8800 GTS (G80) 640MB will be 296% faster than the GeForce 820M in general, because of its greater bandwidth. (explain)

GeForce 8800 GTS (G80) 640MB		63360 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 47360 (296%)

Texel Rate

The GeForce 8800 GTS (G80) 640MB should be quite a bit (about 114%) better at anisotropic filtering than the GeForce 820M. (explain)

GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 13120 (114%)

Pixel Rate

The GeForce 8800 GTS (G80) 640MB will be much (more or less 257%) faster with regards to FSAA than the GeForce 820M, and capable of handling higher resolutions without losing too much performance. (explain)

GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 7384 (257%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (measured in MB per second) that can be transferred over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.