GeForce GT 640 DDR3 vs GeForce GTX 660 Ti

Intro

Compare that to the GeForce GTX 660 Ti, which uses a 28 nm design. nVidia has set the core speed at 915 MHz. The GDDR5 memory is set to run at a frequency of 1500 MHz on this specific card. It features 1344 SPUs as well as 112 TAUs and 24 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

GeForce GTX 660 Ti		6013 points
GeForce GT 640 DDR3		1560 points
	Difference: 4453 (285%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTX 660 Ti		150 Watts
	Difference: 85 Watts (131%)

Memory Bandwidth

In theory, the GeForce GTX 660 Ti should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce GTX 660 Ti		144000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 86976 (153%)

Texel Rate

The GeForce GTX 660 Ti should be a lot (about 256%) more effective at AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 660 Ti		102480 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 73680 (256%)

Pixel Rate

The GeForce GTX 660 Ti should be much (more or less 53%) better at full screen anti-aliasing than the GeForce GT 640 DDR3, and also will be able to handle higher resolutions more effectively. (explain)

GeForce GTX 660 Ti		21960 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 7560 (53%)

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 MB per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the bus width by the speed of its memory. If it uses DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

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