GeForce GTX 850M vs Radeon HD 3870 X2 512MB

Intro

Compare those specifications to the Radeon HD 3870 X2 512MB, which makes use of a 55 nm design. AMD has set the core frequency at 825 MHz. The GDDR3 memory is set to run at a speed of 900 MHz on this card. 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 will be 260% quicker than the GeForce GTX 850M in general, due to its higher data rate. (explain)

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

Texel Rate

The GeForce GTX 850M is a lot (approximately 33%) faster with regards to texture 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 high levels of AA 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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be transferred over the external memory interface in a second. The number is worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster 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 number of texture map elements (texels) that are applied in one second. This is worked out by multiplying the total number 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 applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.