GeForce 8600 GT 512MB DDR2 vs GeForce 9400 GT 256MB

Intro

Compare those specs to the GeForce 9400 GT 256MB, which uses a 65 nm design. nVidia has set the core frequency at 550 MHz. The GDDR2 memory works at a speed of 400 MHz on this card. It features 16 SPUs as well as 8 Texture Address Units and 4 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 512MB DDR2		47 Watts
GeForce 9400 GT 256MB		50 Watts
	Difference: 3 Watts (6%)

Memory Bandwidth

Both cards have the exact same bandwidth, so theoretically they should have identical performance. (explain)

Texel Rate

The GeForce 8600 GT 512MB DDR2 is a lot (more or less 96%) better at AF than the GeForce 9400 GT 256MB. (explain)

GeForce 8600 GT 512MB DDR2		8640 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 4240 (96%)

Pixel Rate

If using a high resolution is important to you, then the GeForce 8600 GT 512MB DDR2 is a better choice, and very much so. (explain)

GeForce 8600 GT 512MB DDR2		4320 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 2120 (96%)

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 max amount of data (in units of MB per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total texture units of the card 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 applied in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.