Radeon HD 6990 vs Radeon R5 M255

Intro

Compare all of that to the Radeon R5 M255, which makes use of a 28 nm design. AMD has set the core frequency at 940 MHz. The DDR3 memory works at a speed of 1000 MHz on this model. It features 320 SPUs as well as 20 Texture Address Units and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 6990 should theoretically be a lot faster than the Radeon R5 M255 overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 304000 (1900%)

Texel Rate

The Radeon HD 6990 should be much (approximately 748%) better at texture filtering than the Radeon R5 M255. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 140560 (748%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6990 is a better choice, by far. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 45600 (606%)

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: Memory bandwidth is the largest amount of information (in units of MB per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. 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 many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.