GeForce 8800 GTS (G80) 640MB 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 specific card. It features 384 SPUs as well as 32 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce 8800 GTS (G80) 640MB		143 Watts
	Difference: 78 Watts (120%)

Memory Bandwidth

In theory, the GeForce 8800 GTS (G80) 640MB should perform a bit faster than the GeForce GT 640 DDR3 overall. (explain)

GeForce 8800 GTS (G80) 640MB		63360 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 6336 (11%)

Texel Rate

The GeForce GT 640 DDR3 is just a bit (approximately 17%) more effective at anisotropic filtering than the GeForce 8800 GTS (G80) 640MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
	Difference: 4176 (17%)

Pixel Rate

The GeForce GT 640 DDR3 is quite a bit (about 40%) more effective at full screen anti-aliasing than the GeForce 8800 GTS (G80) 640MB, and also able to handle higher resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 4140 (40%)

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: Bandwidth is the maximum amount of data (counted in MB per second) that can be transferred over the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, 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 number of texture map elements (texels) that are processed per second. This figure 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the clock 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 output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.