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

Intro

Compare those specifications to the GeForce 9400 GT 256MB, which has a clock speed of 550 MHz and a GDDR2 memory frequency of 400 MHz. It also makes use of a 128-bit bus, and makes use of a 65 nm design. It features 16 SPUs, 8 TAUs, and 4 Raster Operation 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 exactly the same bandwidth, so in theory they should perform the same. (explain)

Texel Rate

The GeForce 8600 GT 512MB DDR2 is quite a bit (about 96%) more effective at anisotropic filtering 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

The GeForce 8600 GT 512MB DDR2 should be quite a bit (approximately 96%) more effective at AA than the GeForce 9400 GT 256MB, and also will be able to handle higher screen resolutions while still performing well. (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: Memory bandwidth is the max amount of information (in units of MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.