GeForce GT 320 vs GeForce GT 420

Intro

Compare those specifications to the GeForce GT 420, which makes use of a 40 nm design. nVidia has clocked the core speed at 700 MHz. The GDDR3 memory runs at a frequency of 900 MHz on this specific model. It features 48 SPUs as well as 8 TAUs and 4 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 320		43 Watts
GeForce GT 420		50 Watts
	Difference: 7 Watts (16%)

Memory Bandwidth

In theory, the GeForce GT 420 should be a bit faster than the GeForce GT 320 overall. (explain)

GeForce GT 420		28800 MB/sec
GeForce GT 320		25280 MB/sec
	Difference: 3520 (14%)

Texel Rate

The GeForce GT 320 should be quite a bit (more or less 131%) better at AF than the GeForce GT 420. (explain)

GeForce GT 320		12960 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 7360 (131%)

Pixel Rate

The GeForce GT 320 should be quite a bit (about 54%) better at FSAA than the GeForce GT 420, and also will be capable of handling higher screen resolutions more effectively. (explain)

GeForce GT 320		4320 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 1520 (54%)

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 (in units of megabytes per second) that can be transferred across the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate 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 fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.