GeForce GT 420 vs Radeon HD 7970

Intro

Compare all of that to the Radeon HD 7970, which features core clock speeds of 925 MHz on the GPU, and 1375 MHz on the 3072 MB of GDDR5 memory. It features 2048 SPUs as well as 128 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
Radeon HD 7970		250 Watts
	Difference: 200 Watts (400%)

Memory Bandwidth

Theoretically, the Radeon HD 7970 should perform much faster than the GeForce GT 420 in general. (explain)

Radeon HD 7970		264000 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 235200 (817%)

Texel Rate

The Radeon HD 7970 will be quite a bit (more or less 2014%) more effective at anisotropic filtering than the GeForce GT 420. (explain)

Radeon HD 7970		118400 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 112800 (2014%)

Pixel Rate

The Radeon HD 7970 is quite a bit (approximately 957%) more effective at FSAA than the GeForce GT 420, and also should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 7970		29600 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 26800 (957%)

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 (measured in megabytes per second) that can be moved across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's 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 applied in one 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.