GeForce GT 320 vs GeForce GT 640 DDR3

Intro

Compare those specs to the GeForce GT 640 DDR3, which has GPU core speed of 900 MHz, and 2048 MB of DDR3 RAM set to run at 1782 MHz through a 128-bit bus. It also features 384 SPUs, 32 Texture Address Units, 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

Theoretically speaking, the GeForce GT 640 DDR3 will be 126% quicker than the GeForce GT 320 overall, due to its higher bandwidth. (explain)

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

Texel Rate

The GeForce GT 640 DDR3 will be quite a bit (approximately 122%) faster with regards to texture 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 a lot (more or less 233%) better at full screen anti-aliasing than the GeForce GT 320, and able to handle higher resolutions more effectively. (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 (measured in MB per second) that can be moved past the external memory interface in a second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better 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 texture map elements (texels) that can be processed per second. This number is worked out by multiplying the total amount of texture units by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.