GeForce GT 640 DDR3 vs GeForce GTS 450 1GB

Intro

Compare those specs to the GeForce GTS 450 1GB, which features GPU core speed of 783 MHz, and 1024 MB of GDDR5 RAM running at 902 MHz through a 128-bit bus. It also is made up of 192 Stream Processors, 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 GTS 450 1GB		106 Watts
	Difference: 41 Watts (63%)

Memory Bandwidth

Performance-wise, the GeForce GTS 450 1GB should theoretically be a little bit better than the GeForce GT 640 DDR3 in general. (explain)

GeForce GTS 450 1GB		57728 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 704 (1%)

Texel Rate

The GeForce GT 640 DDR3 should be a bit (approximately 15%) better at texture filtering than the GeForce GTS 450 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GTS 450 1GB		25056 Mtexels/sec
	Difference: 3744 (15%)

Pixel Rate

The GeForce GT 640 DDR3 will be a small bit (approximately 15%) faster with regards to full screen anti-aliasing than the GeForce GTS 450 1GB, and also capable of handling higher resolutions without slowing down too much. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GTS 450 1GB		12528 Mpixels/sec
	Difference: 1872 (15%)

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 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 card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount 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 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.