GeForce 840M vs Radeon R5 M255

Intro

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

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

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

Texel Rate

The GeForce 840M will be much (about 31%) faster with regards to texture 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 will be just a bit (about 9%) better at anti-aliasing than the Radeon R5 M255, and also able to handle higher screen resolutions without slowing down too much. (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 information (measured in megabytes per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, 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 are applied 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 this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.