Radeon HD 3870 X2 512MB vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which uses a 28 nm design. AMD has set the core speed at 940 MHz. The DDR3 memory is set to run at a speed of 1000 MHz on this particular model. It features 320 SPUs along with 20 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 512MB should in theory be a lot superior to the Radeon R5 M255 overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 3870 X2 512MB is quite a bit (more or less 40%) more effective at AF than the Radeon R5 M255. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 7600 (40%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be quite a bit (more or less 251%) more effective at AA than the Radeon R5 M255, and will be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 18880 (251%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the maximum amount of information (in units of MB per second) that can be transported past the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that 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 number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.