GeForce GT 315 vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which has a clock frequency of 900 MHz and a DDR3 memory speed of 1782 MHz. It also makes use of a 128-bit memory bus, and makes use of a 28 nm design. It features 384 SPUs, 32 TAUs, and 16 Raster Operation Units.

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

Performance-wise, the GeForce GT 640 DDR3 should theoretically be much superior to the GeForce GT 315 in general. (explain)

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

Texel Rate

The GeForce GT 640 DDR3 should be much (approximately 188%) more effective 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 is quite a bit (about 188%) more effective at anti-aliasing than the GeForce GT 315, and will be capable of handling higher screen resolutions without losing too much performance. (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: Bandwidth is the maximum amount of information (measured in MB per second) that can be transferred past the external memory interface in one second. The number is calculated by multiplying the card's interface width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's 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 are applied per second. This number is worked out by multiplying the total number of texture units by the core speed of the chip. The better this number, 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 amount of pixels the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. 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.