GeForce 820M vs Radeon HD 4830 512MB

Intro

Compare those specifications to the Radeon HD 4830 512MB, which has a core clock speed of 575 MHz and a GDDR3 memory speed of 900 MHz. It also uses a 256-bit bus, and uses a 55 nm design. It is made up of 640(128x5) SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
Radeon HD 4830 512MB		95 Watts
	Difference: 80 Watts (533%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4830 512MB is 260% quicker than the GeForce 820M overall, because of its greater bandwidth. (explain)

Radeon HD 4830 512MB		57600 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 41600 (260%)

Texel Rate

The Radeon HD 4830 512MB should be quite a bit (more or less 60%) better at anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 4830 512MB		18400 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 6896 (60%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 4830 512MB is the winner, by a large margin. (explain)

Radeon HD 4830 512MB		9200 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 6324 (220%)

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 maximum amount of data (counted in megabytes per second) that can be moved over the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 once again. If it uses 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 per second. This 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 card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.