Radeon HD 7870 vs Radeon R5 M255

Intro

Compare those specifications to the Radeon R5 M255, which has GPU core speed of 940 MHz, and 2048 MB of DDR3 memory set to run at 1000 MHz through a 64-bit bus. It also is comprised of 320 Stream Processors, 20 TAUs, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7870 should in theory perform quite a bit faster than the Radeon R5 M255 overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 137600 (860%)

Texel Rate

The Radeon HD 7870 will be much (more or less 326%) faster with regards to AF than the Radeon R5 M255. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 61200 (326%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 7870 is superior to the Radeon R5 M255, by far. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 24480 (326%)

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 max amount of data (counted in MB per second) that can be transferred over the external memory interface in one second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, 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 applied in one second. This figure is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

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