GeForce GT 420 vs GeForce GTX 660

Intro

Compare those specifications to the GeForce GTX 660, which features a clock speed of 980 MHz and a GDDR5 memory speed of 1502 MHz. It also uses a 192-bit memory bus, and uses a 28 nm design. It features 960 SPUs, 80 TAUs, and 24 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
GeForce GTX 660		140 Watts
	Difference: 90 Watts (180%)

Memory Bandwidth

Theoretically speaking, the GeForce GTX 660 is 401% quicker than the GeForce GT 420 overall, due to its higher data rate. (explain)

GeForce GTX 660		144192 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 115392 (401%)

Texel Rate

The GeForce GTX 660 is quite a bit (approximately 1300%) more effective at AF than the GeForce GT 420. (explain)

GeForce GTX 660		78400 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 72800 (1300%)

Pixel Rate

The GeForce GTX 660 should be quite a bit (about 740%) better at AA than the GeForce GT 420, and also should be able to handle higher screen resolutions more effectively. (explain)

GeForce GTX 660		23520 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 20720 (740%)

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 (measured in megabytes per second) that can be transferred over the external memory interface within a second. It's worked out by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 number of texture map elements (texels) that are processed in one second. This number is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.