Radeon HD 6990 vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which makes use of a 28 nm design. AMD has clocked the core frequency at 940 MHz. The DDR3 memory runs at a frequency of 1000 MHz on this card. 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

Performance-wise, the Radeon HD 6990 should in theory be much superior to the Radeon R5 M255 in general. (explain)

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

Texel Rate

The Radeon HD 6990 will be quite a bit (more or less 748%) more effective 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

The Radeon HD 6990 is a lot (more or less 606%) more effective at anti-aliasing than the Radeon R5 M255, and will be capable of handling higher screen resolutions while still performing well. (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 max amount of data (measured in megabytes per second) that can be transferred across the external memory interface in a second. The number is calculated by multiplying the bus width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the 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 number of texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total texture units by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to its 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 drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.