GeForce 8800 GS vs GeForce GT 640 DDR3

Intro

Compare those specs to the GeForce GT 640 DDR3, which features GPU core speed of 900 MHz, and 2048 MB of DDR3 memory running at 1782 MHz through a 128-bit bus. It also features 384 Stream Processors, 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 8800 GS		105 Watts
	Difference: 40 Watts (62%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 640 DDR3 is 49% faster than the GeForce 8800 GS overall, due to its higher bandwidth. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8800 GS		38400 MB/sec
	Difference: 18624 (49%)

Texel Rate

The GeForce GT 640 DDR3 will be a bit (approximately 9%) faster with regards to AF than the GeForce 8800 GS. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8800 GS		26400 Mtexels/sec
	Difference: 2400 (9%)

Pixel Rate

The GeForce GT 640 DDR3 should be a lot (approximately 118%) faster with regards to FSAA than the GeForce 8800 GS, and will be capable of handling higher resolutions without losing too much performance. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8800 GS		6600 Mpixels/sec
	Difference: 7800 (118%)

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 (counted in MB per second) that can be transported over the external memory interface within a second. It's calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better 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 texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the card's 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 lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.