GeForce 8800 GTS (G80) 640MB vs GeForce GTX 660

Intro

Compare those specs to the GeForce GTX 660, which has core clock speeds of 980 MHz on the GPU, and 1502 MHz on the 2048 MB of GDDR5 RAM. It features 960 SPUs as well as 80 Texture Address Units and 24 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660		140 Watts
GeForce 8800 GTS (G80) 640MB		143 Watts
	Difference: 3 Watts (2%)

Memory Bandwidth

The GeForce GTX 660 should theoretically be quite a bit faster than the GeForce 8800 GTS (G80) 640MB in general. (explain)

GeForce GTX 660		144192 MB/sec
GeForce 8800 GTS (G80) 640MB		63360 MB/sec
	Difference: 80832 (128%)

Texel Rate

The GeForce GTX 660 should be quite a bit (approximately 218%) more effective at texture filtering than the GeForce 8800 GTS (G80) 640MB. (explain)

GeForce GTX 660		78400 Mtexels/sec
GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
	Difference: 53776 (218%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GTX 660 is a better choice, and very much so. (explain)

GeForce GTX 660		23520 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 13260 (129%)

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 (in units of MB per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory clock speed. In the case of DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 applied per second. This is calculated by multiplying the total texture units by the core speed of the chip. The better 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 can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the core speed of the card. 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 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 reach the max fill rate.