GeForce GT 320 vs GeForce GT 640 DDR3

Intro

Compare those specifications to the GeForce GT 640 DDR3, which has GPU core speed of 900 MHz, and 2048 MB of DDR3 RAM running at 1782 MHz through a 128-bit bus. It also is comprised of 384 SPUs, 32 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 320		43 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 22 Watts (51%)

Memory Bandwidth

In theory, the GeForce GT 640 DDR3 should perform a lot faster than the GeForce GT 320 overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 320		25280 MB/sec
	Difference: 31744 (126%)

Texel Rate

The GeForce GT 640 DDR3 should be much (more or less 122%) faster with regards to anisotropic filtering than the GeForce GT 320. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 320		12960 Mtexels/sec
	Difference: 15840 (122%)

Pixel Rate

The GeForce GT 640 DDR3 should be much (about 233%) more effective at anti-aliasing than the GeForce GT 320, and will be capable of handling higher screen resolutions without losing too much performance. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GT 320		4320 Mpixels/sec
	Difference: 10080 (233%)

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 maximum amount of data (in units of MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.