GeForce 8600 GT 1GB DDR2 vs GeForce GT 640 DDR3

Intro

Compare those specs to the GeForce GT 640 DDR3, which comes with a clock speed of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It is comprised of 384 SPUs, 32 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 1GB DDR2		47 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 18 Watts (38%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 640 DDR3 will be 346% faster than the GeForce 8600 GT 1GB DDR2 overall, due to its higher data rate. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8600 GT 1GB DDR2		12800 MB/sec
	Difference: 44224 (346%)

Texel Rate

The GeForce GT 640 DDR3 should be much (approximately 233%) faster with regards to AF than the GeForce 8600 GT 1GB DDR2. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8600 GT 1GB DDR2		8640 Mtexels/sec
	Difference: 20160 (233%)

Pixel Rate

If running with a high screen resolution 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 1GB 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 data (counted in MB per second) that can be transported over the external memory interface within a second. The number is worked out by multiplying the interface width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.