GeForce GTX 870M vs Radeon HD 4870 2GB

Intro

Compare those specs to the Radeon HD 4870 2GB, which features clock speeds of 750 MHz on the GPU, and 900 MHz on the 2048 MB of GDDR5 memory. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 870M		110 Watts
Radeon HD 4870 2GB		150 Watts
	Difference: 40 Watts (36%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 2GB is 20% quicker than the GeForce GTX 870M overall, due to its higher bandwidth. (explain)

Radeon HD 4870 2GB		115200 MB/sec
GeForce GTX 870M		96000 MB/sec
	Difference: 19200 (20%)

Texel Rate

The GeForce GTX 870M is much (about 251%) better at texture filtering than the Radeon HD 4870 2GB. (explain)

GeForce GTX 870M		105392 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 75392 (251%)

Pixel Rate

The GeForce GTX 870M should be much (approximately 88%) more effective at full screen anti-aliasing than the Radeon HD 4870 2GB, and able to handle higher screen resolutions better. (explain)

GeForce GTX 870M		22584 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 10584 (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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the maximum amount of data (measured in megabytes per second) that can be transferred past the external memory interface in a second. It is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.