GeForce GT 240 GDDR5 1GB vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which uses a 28 nm design. nVidia has clocked the core speed at 900 MHz. The DDR3 RAM works at a frequency of 1782 MHz on this particular model. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GT 240 GDDR5 1GB		70 Watts
	Difference: 5 Watts (8%)

Memory Bandwidth

In theory, the GeForce GT 640 DDR3 should perform a little bit faster than the GeForce GT 240 GDDR5 1GB overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 240 GDDR5 1GB		54400 MB/sec
	Difference: 2624 (5%)

Texel Rate

The GeForce GT 640 DDR3 is much (more or less 64%) more effective at AF than the GeForce GT 240 GDDR5 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 240 GDDR5 1GB		17600 Mtexels/sec
	Difference: 11200 (64%)

Pixel Rate

If using a high screen resolution 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 GT 240 GDDR5 1GB		4400 Mpixels/sec
	Difference: 10000 (227%)

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 (measured in megabytes per second) that can be moved across the external memory interface in one second. It's worked out by multiplying the bus width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in a 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 called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.