Radeon HD 4870 2GB vs Radeon R5 M255

Intro

Compare 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 makes use of a 64-bit memory bus, and uses a 28 nm design. It is made up of 320 SPUs, 20 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 4870 2GB should in theory perform a lot faster than the Radeon R5 M255 overall. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 4870 2GB should be much (more or less 60%) more effective at texture filtering than the Radeon R5 M255. (explain)

Radeon HD 4870 2GB		30000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 11200 (60%)

Pixel Rate

The Radeon HD 4870 2GB is quite a bit (more or less 60%) more effective at AA than the Radeon R5 M255, and also will be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 4870 2GB		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 maximum amount of information (counted in MB per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. If it uses DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.