Radeon HD 7990 vs Radeon R5 M255

Intro

Compare those specifications to the Radeon R5 M255, which makes use of a 28 nm design. AMD has set the core speed at 940 MHz. The DDR3 memory works at a frequency of 1000 MHz on this card. It features 320 SPUs along with 20 TAUs and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 7990 will be 3500% quicker than the Radeon R5 M255 in general, due to its higher bandwidth. (explain)

Radeon HD 7990		576000 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 560000 (3500%)

Texel Rate

The Radeon HD 7990 should be a lot (approximately 1194%) faster with regards to texture filtering than the Radeon R5 M255. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 224400 (1194%)

Pixel Rate

The Radeon HD 7990 should be quite a bit (about 709%) more effective at anti-aliasing than the Radeon R5 M255, and should be able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 53280 (709%)

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 megabytes per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes 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, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.