Radeon HD 4870 1GB vs Radeon R5 M255

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4870 1GB should theoretically be much faster than the Radeon R5 M255 in general. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 4870 1GB should be quite a bit (more or less 60%) better at AF than the Radeon R5 M255. (explain)

Radeon HD 4870 1GB		30000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 11200 (60%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 4870 1GB is superior to the Radeon R5 M255, by a large margin. (explain)

Radeon HD 4870 1GB		12000 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 4480 (60%)

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 information (in units of megabytes per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. 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 number of texture map elements (texels) that are processed per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip 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 number of colour ROPs by the the core 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 lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.