Radeon HD 4850 X2 1GB vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which has a GPU core clock speed of 940 MHz, and 2048 MB of DDR3 memory set to run at 1000 MHz through a 64-bit bus. It also is made up of 320 Stream Processors, 20 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 X2 1GB should perform a lot faster than the Radeon R5 M255 overall. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 111104 (694%)

Texel Rate

The Radeon HD 4850 X2 1GB will be quite a bit (approximately 166%) more effective at anisotropic filtering than the Radeon R5 M255. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 31200 (166%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4850 X2 1GB is a better choice, by a large margin. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 12480 (166%)

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 largest amount of data (measured in MB per second) that can be moved over the external memory interface in one second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, 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 texture map elements (texels) that are processed in one second. This figure 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.