GeForce GT 450 (OEM) vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which features core clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs along with 32 TAUs 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 GT 450 (OEM)		106 Watts
	Difference: 41 Watts (63%)

Memory Bandwidth

In theory, the GeForce GT 450 (OEM) should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce GT 450 (OEM)		96000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 38976 (68%)

Texel Rate

The GeForce GT 640 DDR3 will be much (about 52%) faster with regards to AF than the GeForce GT 450 (OEM). (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 450 (OEM)		18960 Mtexels/sec
	Difference: 9840 (52%)

Pixel Rate

The GeForce GT 450 (OEM) is much (more or less 32%) faster with regards to AA than the GeForce GT 640 DDR3, and capable of handling higher resolutions more effectively. (explain)

GeForce GT 450 (OEM)		18960 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 4560 (32%)

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 megabytes per second) that can be transferred past the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. 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 can be 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 card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the 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 clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.