GeForce 820M vs GeForce 8600 GT 256MB GDDR3

Intro

Compare all that to the GeForce 8600 GT 256MB GDDR3, which uses a 80 nm design. nVidia has clocked the core frequency at 540 MHz. The GDDR3 RAM is set to run at a frequency of 700 MHz on this specific model. It features 32 SPUs along with 16 Texture Address Units and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 8600 GT 256MB GDDR3		47 Watts
	Difference: 32 Watts (213%)

Memory Bandwidth

Theoretically speaking, the GeForce 8600 GT 256MB GDDR3 should be quite a bit faster than the GeForce 820M in general. (explain)

GeForce 8600 GT 256MB GDDR3		22400 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 6400 (40%)

Texel Rate

The GeForce 820M should be a lot (about 33%) better at texture filtering than the GeForce 8600 GT 256MB GDDR3. (explain)

GeForce 820M		11504 Mtexels/sec
GeForce 8600 GT 256MB GDDR3		8640 Mtexels/sec
	Difference: 2864 (33%)

Pixel Rate

The GeForce 8600 GT 256MB GDDR3 should be quite a bit (more or less 50%) faster with regards to anti-aliasing than the GeForce 820M, and capable of handling higher screen resolutions without losing too much performance. (explain)

GeForce 8600 GT 256MB GDDR3		4320 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 1444 (50%)

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 largest amount of information (counted in MB per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high 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 texture units by the core speed of the chip. The higher the texel rate, 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 amount of pixels the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the core 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 rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.