GeForce 840M vs Radeon R5 M255

Intro

Compare all of that to the Radeon R5 M255, which features GPU clock speed of 940 MHz, and 2048 MB of DDR3 RAM running at 1000 MHz through a 64-bit bus. It also features 320 SPUs, 20 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

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

Texel Rate

The GeForce 840M will be quite a bit (about 31%) better at anisotropic filtering than the Radeon R5 M255. (explain)

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

Pixel Rate

The GeForce 840M is just a bit (about 9%) faster with regards to full screen anti-aliasing than the Radeon R5 M255, and also should be capable of handling higher screen resolutions while still performing well. (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 maximum amount of information (counted in MB per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is calculated by multiplying the total number of 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 applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.