GeForce GT 420 vs Radeon HD 6850

Intro

Compare all that to the Radeon HD 6850, which has GPU core speed of 775 MHz, and 1024 MB of GDDR5 memory running at 1000 MHz through a 256-bit bus. It also features 960 SPUs, 48 TAUs, 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 6850		127 Watts
	Difference: 77 Watts (154%)

Memory Bandwidth

In theory, the Radeon HD 6850 is 344% quicker than the GeForce GT 420 overall, because of its higher data rate. (explain)

Radeon HD 6850		128000 MB/sec
GeForce GT 420		28800 MB/sec
	Difference: 99200 (344%)

Texel Rate

The Radeon HD 6850 should be quite a bit (approximately 564%) better at texture filtering than the GeForce GT 420. (explain)

Radeon HD 6850		37200 Mtexels/sec
GeForce GT 420		5600 Mtexels/sec
	Difference: 31600 (564%)

Pixel Rate

The Radeon HD 6850 will be quite a bit (about 786%) more effective at anti-aliasing than the GeForce GT 420, and also will be able to handle higher resolutions while still performing well. (explain)

Radeon HD 6850		24800 Mpixels/sec
GeForce GT 420		2800 Mpixels/sec
	Difference: 22000 (786%)

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 max amount of information (counted in megabytes per second) that can be moved past the external memory interface in a second. It's calculated by multiplying the interface width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of ROPs by the the core clock speed. 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 many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.