GeForce GT 340 1GB vs GeForce GT 640 DDR3

Intro

Compare those specs to the GeForce GT 640 DDR3, which uses a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 RAM runs at a frequency of 1782 MHz on this specific model. It features 384 SPUs along with 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 GT 340 1GB		69 Watts
	Difference: 4 Watts (6%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 640 DDR3 should perform a bit faster than the GeForce GT 340 1GB in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 340 1GB		54400 MB/sec
	Difference: 2624 (5%)

Texel Rate

The GeForce GT 640 DDR3 will be much (about 64%) faster with regards to AF than the GeForce GT 340 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 340 1GB		17600 Mtexels/sec
	Difference: 11200 (64%)

Pixel Rate

The GeForce GT 640 DDR3 is much (more or less 227%) faster with regards to anti-aliasing than the GeForce GT 340 1GB, and also will be capable of handling higher resolutions without losing too much performance. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GT 340 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 max amount of information (measured in megabytes per second) that can be moved across the external memory interface within a second. It's worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster 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 are processed per second. This is worked out by multiplying the total amount of texture units 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output 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 get to the maximum fill rate.