Radeon HD 7990 vs Radeon R5 M255

Intro

Compare all that to the Radeon R5 M255, which uses a 28 nm design. AMD has set the core speed at 940 MHz. The DDR3 memory runs at a frequency of 1000 MHz on this model. 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 is 3500% quicker than the Radeon R5 M255 in general, due to its greater bandwidth. (explain)

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

Texel Rate

The Radeon HD 7990 is much (about 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

If running with a high screen resolution is important to you, then the Radeon HD 7990 is superior to the Radeon R5 M255, by a large margin. (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: Bandwidth is the maximum amount of data (in units of MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs 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 fill rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.