GeForce 840M vs Radeon R5 M255

Intro

Compare those specifications to the Radeon R5 M255, which comes with clock speeds of 940 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 RAM. It features 320 SPUs as well as 20 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Both cards have exactly the same bandwidth, so in theory they should have the same performance. (explain)

Texel Rate

The GeForce 840M is much (more or less 31%) more effective at AF than the Radeon R5 M255. (explain)

GeForce 840M		24696 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 5896 (31%)

Pixel Rate

If running with a high screen resolution is important to you, then the GeForce 840M is the winner, but not by far. (explain)

GeForce 840M		8232 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 712 (9%)

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 moved past the external memory interface in a second. The number is worked out by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

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