GeForce 820M vs GeForce 8600 GT 256MB DDR2

Intro

Compare those specs to the GeForce 8600 GT 256MB DDR2, which uses a 80 nm design. nVidia has set the core frequency at 540 MHz. The DDR2 RAM works at a speed of 400 MHz on this particular model. It features 32 SPUs along with 16 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 8600 GT 256MB DDR2		47 Watts
	Difference: 32 Watts (213%)

Memory Bandwidth

Theoretically speaking, the GeForce 820M is 25% faster than the GeForce 8600 GT 256MB DDR2 overall, because of its higher data rate. (explain)

GeForce 820M		16000 MB/sec
GeForce 8600 GT 256MB DDR2		12800 MB/sec
	Difference: 3200 (25%)

Texel Rate

The GeForce 820M will be much (about 33%) more effective at texture filtering than the GeForce 8600 GT 256MB DDR2. (explain)

GeForce 820M		11504 Mtexels/sec
GeForce 8600 GT 256MB DDR2		8640 Mtexels/sec
	Difference: 2864 (33%)

Pixel Rate

If running with a high screen resolution is important to you, then the GeForce 8600 GT 256MB DDR2 is the winner, by far. (explain)

GeForce 8600 GT 256MB DDR2		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: Bandwidth is the largest amount of data (measured in megabytes per second) that can be transferred over the external memory interface within a second. It's worked out by multiplying the interface width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better 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 texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the video 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 can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.