GeForce 820M vs Radeon HD 3850 X2

Intro

Compare those specifications to the Radeon HD 3850 X2, which uses a 55 nm design. AMD has set the core frequency at 668 MHz. The GDDR3 memory works at a speed of 828 MHz on this model. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3850 X2 should in theory be a lot better than the GeForce 820M overall. (explain)

Radeon HD 3850 X2		105984 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 89984 (562%)

Texel Rate

The Radeon HD 3850 X2 is quite a bit (more or less 86%) better at anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 3850 X2		21376 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 9872 (86%)

Pixel Rate

The Radeon HD 3850 X2 is a lot (more or less 643%) better at anti-aliasing than the GeForce 820M, and will be able to handle higher screen resolutions more effectively. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 18500 (643%)

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: Bandwidth is the max amount of data (counted in MB per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 again. If it uses 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 can be processed in one second. This number is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.