GeForce GT 640 DDR3 vs Radeon R9 M390X

Intro

Compare those specs to the Radeon R9 M390X, which uses a 28 nm design. AMD has clocked the core speed at 723 MHz. The GDDR5 RAM works at a frequency of 1250 MHz on this particular model. It features 2048 SPUs as well as 128 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon R9 M390X		125 Watts
	Difference: 60 Watts (92%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 M390X should be 181% faster than the GeForce GT 640 DDR3 overall, due to its higher bandwidth. (explain)

Radeon R9 M390X		160000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 102976 (181%)

Texel Rate

The Radeon R9 M390X will be a lot (more or less 221%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Radeon R9 M390X		92544 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 63744 (221%)

Pixel Rate

The Radeon R9 M390X should be much (approximately 61%) better at anti-aliasing than the GeForce GT 640 DDR3, and also will be able to handle higher resolutions while still performing well. (explain)

Radeon R9 M390X		23136 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 8736 (61%)

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 maximum amount of information (measured in MB per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's bus 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 faster 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 texture map elements (texels) that are applied per second. This figure 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the core clock speed. 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 lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.