Radeon HD 6790 vs Radeon R5 M255

Intro

Compare all that to the Radeon R5 M255, which comes with a core clock speed of 940 MHz and a DDR3 memory speed of 1000 MHz. It also uses a 64-bit bus, and uses a 28 nm design. It is comprised of 320 SPUs, 20 TAUs, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 6790 should theoretically be much superior to the Radeon R5 M255 overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 118400 (740%)

Texel Rate

The Radeon HD 6790 will be much (approximately 79%) more effective at anisotropic filtering than the Radeon R5 M255. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 14800 (79%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 6790 is a better choice, by a large margin. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 5920 (79%)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (counted in megabytes per second) that can be moved past the external memory interface in a second. It is calculated by multiplying the interface width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 number of texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total number 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 applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.