GeForce GT 240 GDDR5 vs GeForce GT 420

Intro

Compare those specs to the GeForce GT 420, which makes use of a 40 nm design. nVidia has set the core speed at 700 MHz. The GDDR3 RAM is set to run at a speed of 900 MHz on this model. It features 48 SPUs as well as 8 Texture Address Units and 4 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
GeForce GT 240 GDDR5		70 Watts
	Difference: 20 Watts (40%)

Memory Bandwidth

Theoretically speaking, the GeForce GT 240 GDDR5 should be 89% quicker than the GeForce GT 420 overall, due to its higher data rate. (explain)

GeForce GT 240 GDDR5		54400 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 25600 (89%)

Texel Rate

The GeForce GT 240 GDDR5 is much (approximately 214%) faster with regards to AF than the GeForce GT 420. (explain)

GeForce GT 240 GDDR5		17600 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 12000 (214%)

Pixel Rate

The GeForce GT 240 GDDR5 should be a lot (about 57%) faster with regards to full screen anti-aliasing than the GeForce GT 420, and should be able to handle higher resolutions while still performing well. (explain)

GeForce GT 240 GDDR5		4400 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 1600 (57%)

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 (counted in MB per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If it uses 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, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the 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 number of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines 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 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 potential to reach the maximum fill rate.