GeForce 820M vs Radeon R5 M255

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Both cards have exactly the same memory bandwidth, so theoretically they should have identical performance. (explain)

Texel Rate

The Radeon R5 M255 will be much (about 63%) faster with regards to anisotropic filtering than the GeForce 820M. (explain)

Radeon R5 M255		18800 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 7296 (63%)

Pixel Rate

The Radeon R5 M255 should be a lot (about 161%) better at full screen anti-aliasing than the GeForce 820M, and also will be capable of handling higher resolutions without slowing down too much. (explain)

Radeon R5 M255		7520 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 4644 (161%)

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 largest amount of information (measured in MB per second) that can be transferred across the external memory interface in one second. It's worked out by multiplying the card's interface width by its memory speed. In the case of DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total texture units of the card by the core clock 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 processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to the local memory in one 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 - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.