GeForce GTX 850M vs Radeon HD 4870 2GB

Intro

Compare all that to the Radeon HD 4870 2GB, which uses a 55 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 memory works at a frequency of 900 MHz on this model. 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 2GB		150 Watts
	Difference: 110 Watts (275%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 2GB should theoretically be much better than the GeForce GTX 850M overall. (explain)

Radeon HD 4870 2GB		115200 MB/sec
GeForce GTX 850M		32000 MB/sec
	Difference: 83200 (260%)

Texel Rate

The GeForce GTX 850M will be just a bit (approximately 17%) more effective at texture filtering than the Radeon HD 4870 2GB. (explain)

GeForce GTX 850M		35040 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 5040 (17%)

Pixel Rate

The GeForce GTX 850M should be a little bit (about 17%) faster with regards to full screen anti-aliasing than the Radeon HD 4870 2GB, and capable of handling higher resolutions without losing too much performance. (explain)

GeForce GTX 850M		14016 Mpixels/sec
Radeon HD 4870 2GB		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 data (counted in MB per second) that can be transferred past the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total amount 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 applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core clock speed. 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 lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.