GeForce 8800 GTS (G92) vs GeForce GT 640 DDR3

Intro

Compare those specifications to the GeForce GT 640 DDR3, which features a GPU core clock speed of 900 MHz, and 2048 MB of DDR3 memory set to run at 1782 MHz through a 128-bit bus. It also is made up of 384 SPUs, 32 TAUs, 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 8800 GTS (G92)		135 Watts
	Difference: 70 Watts (108%)

Memory Bandwidth

As far as performance goes, the GeForce 8800 GTS (G92) should theoretically be just a bit superior to the GeForce GT 640 DDR3 in general. (explain)

GeForce 8800 GTS (G92)		62080 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 5056 (9%)

Texel Rate

The GeForce 8800 GTS (G92) should be much (approximately 44%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)

GeForce 8800 GTS (G92)		41600 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 12800 (44%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is a better choice, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GTS (G92)		10400 Mpixels/sec
	Difference: 4000 (38%)

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 largest amount of data (measured in megabytes per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the graphics card will be at handling 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 card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines 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 rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.