GeForce 8400 GS 512MB vs GeForce 8600 GT 512MB DDR2

Intro

Compare those specs to the GeForce 8600 GT 512MB DDR2, which has a core clock speed of 540 MHz and a DDR2 memory frequency of 400 MHz. It also features a 128-bit bus, and makes use of a 80 nm design. It is comprised of 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 8400 GS 512MB		40 Watts
GeForce 8600 GT 512MB DDR2		47 Watts
	Difference: 7 Watts (18%)

Memory Bandwidth

In theory, the GeForce 8600 GT 512MB DDR2 should be 100% quicker than the GeForce 8400 GS 512MB overall, due to its higher data rate. (explain)

GeForce 8600 GT 512MB DDR2		12800 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 6400 (100%)

Texel Rate

The GeForce 8600 GT 512MB DDR2 will be a lot (about 66%) faster with regards to AF than the GeForce 8400 GS 512MB. (explain)

GeForce 8600 GT 512MB DDR2		8640 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 3440 (66%)

Pixel Rate

If using a high screen resolution is important to you, then the GeForce 8600 GT 512MB DDR2 is a better choice, by far. (explain)

GeForce 8600 GT 512MB DDR2		4320 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 1720 (66%)

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 MB per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.