GeForce GTX 870M vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which comes with GPU clock speed of 940 MHz, and 2048 MB of DDR3 RAM set to run at 1000 MHz through a 64-bit bus. It also is made up of 320 SPUs, 20 TAUs, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the GeForce GTX 870M should theoretically be a lot better than the Radeon R5 M255 overall. (explain)

GeForce GTX 870M		96000 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 80000 (500%)

Texel Rate

The GeForce GTX 870M will be quite a bit (about 461%) faster with regards to anisotropic filtering than the Radeon R5 M255. (explain)

GeForce GTX 870M		105392 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 86592 (461%)

Pixel Rate

The GeForce GTX 870M is a lot (approximately 200%) more effective at full screen anti-aliasing than the Radeon R5 M255, and also should be capable of handling higher resolutions more effectively. (explain)

GeForce GTX 870M		22584 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 15064 (200%)

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 information (counted in MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 per second. This is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.