GeForce 820M vs Radeon HD 3870 512MB

Intro

Compare those specifications to the Radeon HD 3870 512MB, which has GPU clock speed of 775 MHz, and 512 MB of GDDR3 RAM running at 900 MHz through a 256-bit bus. It also features 320(64x5) Stream Processors, 16 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 3870 512MB		106 Watts
	Difference: 91 Watts (607%)

Memory Bandwidth

The Radeon HD 3870 512MB should in theory perform quite a bit faster than the GeForce 820M overall. (explain)

Radeon HD 3870 512MB		57600 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 41600 (260%)

Texel Rate

The Radeon HD 3870 512MB will be a small bit (approximately 8%) faster with regards to anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 3870 512MB		12400 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 896 (8%)

Pixel Rate

The Radeon HD 3870 512MB is much (about 331%) better at AA than the GeForce 820M, and should be capable of handling higher resolutions better. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 9524 (331%)

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 (counted in megabytes per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high 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 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 in a second.

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