GeForce 8600 GT 256MB DDR2 vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which has GPU clock speed of 900 MHz, and 2048 MB of DDR3 RAM set to run at 1782 MHz through a 128-bit bus. It also features 384 SPUs, 32 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 256MB DDR2		47 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 18 Watts (38%)

Memory Bandwidth

In theory, the GeForce GT 640 DDR3 should perform much faster than the GeForce 8600 GT 256MB DDR2 in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8600 GT 256MB DDR2		12800 MB/sec
	Difference: 44224 (346%)

Texel Rate

The GeForce GT 640 DDR3 should be quite a bit (more or less 233%) faster with regards to anisotropic filtering than the GeForce 8600 GT 256MB DDR2. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8600 GT 256MB DDR2		8640 Mtexels/sec
	Difference: 20160 (233%)

Pixel Rate

If using high levels of AA is important to you, then the GeForce GT 640 DDR3 is the winner, and very much so. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8600 GT 256MB DDR2		4320 Mpixels/sec
	Difference: 10080 (233%)

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 largest amount of information (in units of MB per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the bus width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory in one 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 - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.