GeForce GT 640 DDR3 vs Radeon R5 M255

Intro

Compare all of that to the Radeon R5 M255, which uses a 28 nm design. AMD has set the core speed at 940 MHz. The DDR3 memory works at a speed of 1000 MHz on this particular model. It features 320 SPUs as well as 20 TAUs and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the GeForce GT 640 DDR3 should perform quite a bit faster than the Radeon R5 M255 in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 41024 (256%)

Texel Rate

The GeForce GT 640 DDR3 will be a lot (approximately 53%) faster with regards to texture filtering than the Radeon R5 M255. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 10000 (53%)

Pixel Rate

If using a high resolution is important to you, then the GeForce GT 640 DDR3 is a better choice, by a large margin. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 6880 (91%)

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: Memory bandwidth is the max amount of information (counted in megabytes per second) that can be moved past the external memory interface in one second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.