GeForce 8800 GT 512MB vs GeForce GT 420

Intro

Compare those specs to the GeForce GT 420, which features a GPU core clock speed of 700 MHz, and 2048 MB of GDDR3 RAM set to run at 900 MHz through a 128-bit bus. It also features 48 Stream Processors, 8 TAUs, and 4 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
GeForce 8800 GT 512MB		105 Watts
	Difference: 55 Watts (110%)

Memory Bandwidth

The GeForce 8800 GT 512MB, in theory, should be much faster than the GeForce GT 420 overall. (explain)

GeForce 8800 GT 512MB		57600 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 28800 (100%)

Texel Rate

The GeForce 8800 GT 512MB is quite a bit (about 500%) faster with regards to anisotropic filtering than the GeForce GT 420. (explain)

GeForce 8800 GT 512MB		33600 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 28000 (500%)

Pixel Rate

The GeForce 8800 GT 512MB should be quite a bit (about 243%) better at anti-aliasing than the GeForce GT 420, and also will be able to handle higher screen resolutions without losing too much performance. (explain)

GeForce 8800 GT 512MB		9600 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 6800 (243%)

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 MB per second) that can be transported past the external memory interface in a second. It's worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per 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 video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.