GeForce GT 640 DDR3 vs Radeon R9 M290X

Intro

Compare those specifications to the Radeon R9 M290X, which features a GPU core clock speed of 850 MHz, and 4096 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also features 1280 Stream Processors, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon R9 M290X		100 Watts
	Difference: 35 Watts (54%)

Memory Bandwidth

As far as performance goes, the Radeon R9 M290X should in theory be much better than the GeForce GT 640 DDR3 in general. (explain)

Radeon R9 M290X		153600 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 96576 (169%)

Texel Rate

The Radeon R9 M290X will be much (approximately 136%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Radeon R9 M290X		68000 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 39200 (136%)

Pixel Rate

The Radeon R9 M290X is a lot (more or less 89%) faster with regards to anti-aliasing than the GeForce GT 640 DDR3, and also should be able to handle higher resolutions better. (explain)

Radeon R9 M290X		27200 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 12800 (89%)

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 (counted in megabytes per second) that can be transferred across the external memory interface in a second. It's worked out by multiplying the bus width by its memory speed. If it uses DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory per 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 drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.