GeForce 8600 GTS vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which features a clock frequency of 900 MHz and a DDR3 memory speed of 1782 MHz. It also uses a 128-bit bus, and makes use of a 28 nm design. It is made up of 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8600 GTS		75 Watts
	Difference: 10 Watts (15%)

Memory Bandwidth

Performance-wise, the GeForce GT 640 DDR3 should in theory be quite a bit better than the GeForce 8600 GTS in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8600 GTS		32000 MB/sec
	Difference: 25024 (78%)

Texel Rate

The GeForce GT 640 DDR3 should be quite a bit (about 167%) faster with regards to AF than the GeForce 8600 GTS. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8600 GTS		10800 Mtexels/sec
	Difference: 18000 (167%)

Pixel Rate

The GeForce GT 640 DDR3 is a lot (approximately 167%) faster with regards to full screen anti-aliasing than the GeForce 8600 GTS, and should be capable of handling higher screen resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8600 GTS		5400 Mpixels/sec
	Difference: 9000 (167%)

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 information (measured in MB per second) that can be moved over the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total texture units by the core clock 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 the video card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.