GeForce 820M vs Radeon HD 3870 X2 512MB

Intro

Compare those specs to the Radeon HD 3870 X2 512MB, which has clock speeds of 825 MHz on the GPU, and 900 MHz on the 512 MB of GDDR3 RAM. It features 320(64x5) SPUs as well as 16 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 512MB is 620% faster than the GeForce 820M in general, because of its greater data rate. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 3870 X2 512MB is much (more or less 129%) more effective at anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 14896 (129%)

Pixel Rate

The Radeon HD 3870 X2 512MB is much (approximately 818%) more effective at AA than the GeForce 820M, and also able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 23524 (818%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (counted in MB per second) that can be transported over the external memory interface within a second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 are processed 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 card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant 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.