GeForce GTX 850M vs Radeon HD 3870 X2 512MB

Intro

Compare all of that to the Radeon HD 3870 X2 512MB, which uses a 55 nm design. AMD has set the core speed at 825 MHz. The GDDR3 memory works at a frequency of 900 MHz on this particular card. It features 320(64x5) SPUs as well as 16 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 512MB should be 260% faster than the GeForce GTX 850M overall, because of its higher bandwidth. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
GeForce GTX 850M		32000 MB/sec
	Difference: 83200 (260%)

Texel Rate

The GeForce GTX 850M will be much (approximately 33%) better at anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

GeForce GTX 850M		35040 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 8640 (33%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 3870 X2 512MB is the winner, by a large margin. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
GeForce GTX 850M		14016 Mpixels/sec
	Difference: 12384 (88%)

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 maximum amount of data (counted in MB per second) that can be transferred across the external memory interface within a second. It is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This is calculated by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the 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 maximum amount of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated 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 outputting the pixels (image) to the screen. The actual pixel fill 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 reach the max fill rate.