GeForce GTX 870M vs Radeon R9 M270X

Intro

Compare those specifications to the Radeon R9 M270X, which features GPU clock speed of 725 MHz, and 2048 MB of GDDR5 RAM set to run at 1125 MHz through a 128-bit bus. It also is made up of 640 SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the GeForce GTX 870M should be 33% faster than the Radeon R9 M270X in general, due to its higher bandwidth. (explain)

GeForce GTX 870M		96000 MB/sec
Radeon R9 M270X		72000 MB/sec
	Difference: 24000 (33%)

Texel Rate

The GeForce GTX 870M is a lot (about 263%) faster with regards to anisotropic filtering than the Radeon R9 M270X. (explain)

GeForce GTX 870M		105392 Mtexels/sec
Radeon R9 M270X		29000 Mtexels/sec
	Difference: 76392 (263%)

Pixel Rate

The GeForce GTX 870M is much (approximately 95%) more effective at AA than the Radeon R9 M270X, and also will be able to handle higher resolutions without losing too much performance. (explain)

GeForce GTX 870M		22584 Mpixels/sec
Radeon R9 M270X		11600 Mpixels/sec
	Difference: 10984 (95%)

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 largest amount of data (in units of MB per second) that can be moved across the external memory interface in one second. The number is calculated by multiplying the interface width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.