GeForce GT 420 vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which comes with GPU core speed of 1000 MHz, and 2048 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also features 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 420		50 Watts
Radeon HD 7870		175 Watts
	Difference: 125 Watts (250%)

Memory Bandwidth

The Radeon HD 7870 should theoretically be quite a bit faster than the GeForce GT 420 overall. (explain)

Radeon HD 7870		153600 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 124800 (433%)

Texel Rate

The Radeon HD 7870 will be much (approximately 1329%) faster with regards to AF than the GeForce GT 420. (explain)

Radeon HD 7870		80000 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 74400 (1329%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7870 is a better choice, and very much so. (explain)

Radeon HD 7870		32000 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 29200 (1043%)

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 maximum amount of information (in units of MB per second) that can be transferred past the external memory interface within a second. It is worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most 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 amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes 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, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.