GeForce 8600 GT 256MB DDR2 vs GeForce GT 420

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 256MB DDR2		47 Watts
GeForce GT 420		50 Watts
	Difference: 3 Watts (6%)

Memory Bandwidth

The GeForce GT 420 should in theory perform much faster than the GeForce 8600 GT 256MB DDR2 overall. (explain)

GeForce GT 420		28800 MB/sec
GeForce 8600 GT 256MB DDR2		12800 MB/sec
	Difference: 16000 (125%)

Texel Rate

The GeForce 8600 GT 256MB DDR2 will be a lot (about 54%) better at anisotropic filtering than the GeForce GT 420. (explain)

GeForce 8600 GT 256MB DDR2		8640 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 3040 (54%)

Pixel Rate

The GeForce 8600 GT 256MB DDR2 should be much (about 54%) better at full screen anti-aliasing than the GeForce GT 420, and should be able to handle higher screen resolutions while still performing well. (explain)

GeForce 8600 GT 256MB DDR2		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: Memory bandwidth is the max amount of information (measured in MB per second) that can be transported past the external memory interface in a second. It is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs 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 fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.