GeForce 820M vs GeForce 8600 GT 512MB DDR2

Intro

Compare those specs to the GeForce 8600 GT 512MB DDR2, which comes with a core clock speed of 540 MHz and a DDR2 memory speed of 400 MHz. It also uses a 128-bit bus, and uses a 80 nm design. It features 32 SPUs, 16 TAUs, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 8600 GT 512MB DDR2		47 Watts
	Difference: 32 Watts (213%)

Memory Bandwidth

The GeForce 820M should in theory be quite a bit faster than the GeForce 8600 GT 512MB DDR2 overall. (explain)

GeForce 820M		16000 MB/sec
GeForce 8600 GT 512MB 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 512MB DDR2. (explain)

GeForce 820M		11504 Mtexels/sec
GeForce 8600 GT 512MB DDR2		8640 Mtexels/sec
	Difference: 2864 (33%)

Pixel Rate

The GeForce 8600 GT 512MB DDR2 should be a lot (more or less 50%) more effective at full screen anti-aliasing than the GeForce 820M, and will be able to handle higher resolutions without losing too much performance. (explain)

GeForce 8600 GT 512MB 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 maximum amount of data (counted in MB per second) that can be transported over the external memory interface in one second. It's worked out by multiplying the bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount 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 per second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.