GeForce GTX 850M vs Radeon HD 4870 X2

Intro

Compare those specifications to the Radeon HD 4870 X2, which features a clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also uses a 256-bit bus, and uses a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 850M		40 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 310 Watts (775%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 is 620% faster than the GeForce GTX 850M in general, due to its greater data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
GeForce GTX 850M		32000 MB/sec
	Difference: 198400 (620%)

Texel Rate

The Radeon HD 4870 X2 should be much (approximately 71%) better at texture filtering than the GeForce GTX 850M. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
GeForce GTX 850M		35040 Mtexels/sec
	Difference: 24960 (71%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 4870 X2 is the winner, by far. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
GeForce GTX 850M		14016 Mpixels/sec
	Difference: 9984 (71%)

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 information (measured in megabytes per second) that can be moved past the external memory interface in a second. It is worked out by multiplying the bus width by the speed of its memory. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total texture units by the core speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.