GeForce GTX 850M vs Radeon HD 4870 1GB

Intro

Compare those specifications to the Radeon HD 4870 1GB, which features clock speeds of 750 MHz on the GPU, and 900 MHz on the 1024 MB of GDDR5 memory. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 850M		40 Watts
Radeon HD 4870 1GB		150 Watts
	Difference: 110 Watts (275%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 1GB should theoretically be a lot better than the GeForce GTX 850M in general. (explain)

Radeon HD 4870 1GB		115200 MB/sec
GeForce GTX 850M		32000 MB/sec
	Difference: 83200 (260%)

Texel Rate

The GeForce GTX 850M should be a little bit (approximately 17%) more effective at texture filtering than the Radeon HD 4870 1GB. (explain)

GeForce GTX 850M		35040 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 5040 (17%)

Pixel Rate

The GeForce GTX 850M is a little bit (approximately 17%) more effective at FSAA than the Radeon HD 4870 1GB, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

GeForce GTX 850M		14016 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 2016 (17%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of information (measured in megabytes per second) that can be moved across the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, 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 amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total amount 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 processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output 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 max fill rate.