Radeon HD 7870 vs Radeon R5 M255

Intro

Compare those specs to the Radeon R5 M255, which comes with a clock speed of 940 MHz and a DDR3 memory frequency of 1000 MHz. It also features a 64-bit bus, and makes use of a 28 nm design. It is made up of 320 SPUs, 20 TAUs, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7870 should in theory be a lot faster than the Radeon R5 M255 overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 137600 (860%)

Texel Rate

The Radeon HD 7870 should be quite a bit (approximately 326%) faster with regards to AF than the Radeon R5 M255. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 61200 (326%)

Pixel Rate

The Radeon HD 7870 will be quite a bit (approximately 326%) faster with regards to full screen anti-aliasing than the Radeon R5 M255, and also will be able to handle higher resolutions better. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 24480 (326%)

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: Memory bandwidth is the max amount of data (in units of MB per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.