GeForce GT 640 DDR3 vs Nvidia Titan X

Intro

Compare those specifications to the Nvidia Titan X, which features core clock speeds of 1417 MHz on the GPU, and 1251 MHz on the 12288 MB of GDDR5X RAM. It features 3584 SPUs along with 224 Texture Address Units and 96 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Nvidia Titan X		250 Watts
	Difference: 185 Watts (285%)

Memory Bandwidth

In theory, the Nvidia Titan X should be 762% faster than the GeForce GT 640 DDR3 overall, due to its higher bandwidth. (explain)

Nvidia Titan X		491520 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 434496 (762%)

Texel Rate

The Nvidia Titan X is much (about 1002%) better at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Nvidia Titan X		317408 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 288608 (1002%)

Pixel Rate

The Nvidia Titan X will be quite a bit (approximately 845%) faster with regards to FSAA than the GeForce GT 640 DDR3, and capable of handling higher resolutions more effectively. (explain)

Nvidia Titan X		136032 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 121632 (845%)

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 max amount of data (measured in megabytes per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the interface width by its memory clock speed. If the card has DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total amount of texture units of the card by the core clock 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 maximum number of pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.