GeForce 8600 GT 512MB GDDR3 vs GeForce GT 640 DDR3

Intro

Compare those specifications to the GeForce GT 640 DDR3, which makes use of a 28 nm design. nVidia has set the core frequency at 900 MHz. The DDR3 memory runs at a speed of 1782 MHz on this model. It features 384 SPUs along with 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 512MB GDDR3		47 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 18 Watts (38%)

Memory Bandwidth

As far as performance goes, the GeForce GT 640 DDR3 should in theory be much better than the GeForce 8600 GT 512MB GDDR3 overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8600 GT 512MB GDDR3		22400 MB/sec
	Difference: 34624 (155%)

Texel Rate

The GeForce GT 640 DDR3 should be quite a bit (more or less 233%) more effective at texture filtering than the GeForce 8600 GT 512MB GDDR3. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8600 GT 512MB GDDR3		8640 Mtexels/sec
	Difference: 20160 (233%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce GT 640 DDR3 is superior to the GeForce 8600 GT 512MB GDDR3, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8600 GT 512MB GDDR3		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 maximum amount of data (counted in MB per second) that can be transferred over the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the video 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 can possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.