GeForce 820M vs GeForce 8600 GT 256MB DDR2

Intro

Compare all that to the GeForce 8600 GT 256MB DDR2, which comes with a clock frequency of 540 MHz and a DDR2 memory frequency of 400 MHz. It also features a 128-bit memory bus, and uses a 80 nm design. It features 32 SPUs, 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 DDR2		47 Watts
	Difference: 32 Watts (213%)

Memory Bandwidth

In theory, the GeForce 820M will be 25% quicker than the GeForce 8600 GT 256MB DDR2 in general, because of its greater bandwidth. (explain)

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

Texel Rate

The GeForce 820M will be quite a bit (approximately 33%) faster with regards to anisotropic 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

The GeForce 8600 GT 256MB DDR2 will be much (about 50%) better at FSAA than the GeForce 820M, and also will be able to handle higher resolutions without losing too much performance. (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: Memory bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. The number is calculated by multiplying the interface width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 get to the max fill rate.