Radeon HD 7870 XT vs Radeon R5 M255

Intro

Compare all that to the Radeon R5 M255, which features clock speeds of 940 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 memory. It features 320 SPUs as well as 20 TAUs and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 7870 XT is 1100% quicker than the Radeon R5 M255 overall, due to its greater data rate. (explain)

Radeon HD 7870 XT		192000 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 176000 (1100%)

Texel Rate

The Radeon HD 7870 XT is quite a bit (about 372%) more effective at texture filtering than the Radeon R5 M255. (explain)

Radeon HD 7870 XT		88800 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 70000 (372%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7870 XT is superior to the Radeon R5 M255, by a large margin. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 22080 (294%)

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 (measured in megabytes per second) that can be transferred across the external memory interface within a second. The number is calculated by multiplying the interface width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.