Radeon HD 4870 1GB vs Radeon R5 M255

Intro

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

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 1GB should be much faster than the Radeon R5 M255 overall. (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 much (about 60%) more effective at anisotropic filtering 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 the winner, and very much so. (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: Memory bandwidth is the max amount of data (measured in MB per second) that can be transferred past the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels 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 worked out by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.