GeForce 8600 GT 256MB GDDR3 vs GeForce GT 420

Intro

Compare that to the GeForce GT 420, which uses 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 along with 8 TAUs and 4 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 256MB GDDR3		47 Watts
GeForce GT 420		50 Watts
	Difference: 3 Watts (6%)

Memory Bandwidth

Performance-wise, the GeForce GT 420 should in theory be much better than the GeForce 8600 GT 256MB GDDR3 in general. (explain)

GeForce GT 420		28800 MB/sec
GeForce 8600 GT 256MB GDDR3		22400 MB/sec
	Difference: 6400 (29%)

Texel Rate

The GeForce 8600 GT 256MB GDDR3 will be quite a bit (more or less 54%) more effective at texture filtering than the GeForce GT 420. (explain)

GeForce 8600 GT 256MB GDDR3		8640 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 3040 (54%)

Pixel Rate

If running with a high screen resolution is important to you, then the GeForce 8600 GT 256MB GDDR3 is superior to the GeForce GT 420, by far. (explain)

GeForce 8600 GT 256MB GDDR3		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 information (in units of megabytes per second) that can be transported past the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 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, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per 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 higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could 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 colour ROPs by the clock speed of the card. 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 many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.