GeForce GT 315 vs GeForce GT 640 DDR3

Intro

Compare all of that to the GeForce GT 640 DDR3, which has a GPU core clock speed of 900 MHz, and 2048 MB of DDR3 memory set to run at 1782 MHz through a 128-bit bus. It also is comprised of 384 Stream Processors, 32 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 315		52 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 13 Watts (25%)

Memory Bandwidth

The GeForce GT 640 DDR3 should in theory perform a lot faster than the GeForce GT 315 overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 315		25280 MB/sec
	Difference: 31744 (126%)

Texel Rate

The GeForce GT 640 DDR3 will be a lot (about 188%) better at texture filtering than the GeForce GT 315. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 315		10000 Mtexels/sec
	Difference: 18800 (188%)

Pixel Rate

The GeForce GT 640 DDR3 will be quite a bit (approximately 188%) better at FSAA than the GeForce GT 315, and should be capable of handling higher screen resolutions better. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GT 315		5000 Mpixels/sec
	Difference: 9400 (188%)

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 largest amount of data (counted in MB per second) that can be transported past the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total texture units by the core speed of the chip. The better this number, the better the graphics 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 most pixels the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the clock 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 also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.