GeForce GT 420 vs Radeon HD 3870 X2 1GB

Intro

Compare all of that to the Radeon HD 3870 X2 1GB, which has GPU core speed of 825 MHz, and 1024 MB of GDDR4 memory set to run at 1126 MHz through a 256-bit bus. It also is comprised of 320(64x5) Stream Processors, 16 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 1GB, in theory, should perform a lot faster than the GeForce GT 420 overall. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 115328 (400%)

Texel Rate

The Radeon HD 3870 X2 1GB is quite a bit (approximately 371%) faster with regards to texture filtering than the GeForce GT 420. (explain)

Radeon HD 3870 X2 1GB		26400 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 20800 (371%)

Pixel Rate

The Radeon HD 3870 X2 1GB is quite a bit (approximately 843%) more effective at anti-aliasing than the GeForce GT 420, and should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 23600 (843%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (measured in MB per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better 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 texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units 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 rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.