GeForce 8800 GTS (G92) vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which comes with a core clock speed of 900 MHz and a DDR3 memory speed of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It is comprised of 384 SPUs, 32 Texture Address Units, and 16 ROPs.

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

In theory, the GeForce 8800 GTS (G92) should perform a small bit faster than 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 a lot (more or less 44%) faster with regards to AF 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

The GeForce GT 640 DDR3 should be quite a bit (approximately 38%) more effective at AA than the GeForce 8800 GTS (G92), and should be able to handle higher resolutions while still performing well. (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: Memory bandwidth is the max amount of information (in units of megabytes per second) that can be transferred across the external memory interface within a second. It is worked out by multiplying the interface width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour 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 is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.