Radeon HD 3870 X2 1GB vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which features core clock speeds of 940 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 memory. It features 320 SPUs as well as 20 TAUs 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 1GB should in theory be much superior to the Radeon R5 M255 overall. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 128128 (801%)

Texel Rate

The Radeon HD 3870 X2 1GB will be quite a bit (about 40%) faster with regards to texture filtering than the Radeon R5 M255. (explain)

Radeon HD 3870 X2 1GB		26400 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 7600 (40%)

Pixel Rate

The Radeon HD 3870 X2 1GB should be much (about 251%) more effective at FSAA than the Radeon R5 M255, and should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		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 max amount of information (measured in megabytes per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the card's interface width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This is worked out by multiplying the total texture units by the core 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 maximum amount of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.