GeForce GT 640 DDR3 vs Radeon R9 M275X

Intro

Compare those specs to the Radeon R9 M275X, which uses a 28 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 RAM runs at a speed of 1125 MHz on this model. It features 640 SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M275X		50 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 15 Watts (30%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 M275X should be 26% quicker than the GeForce GT 640 DDR3 overall, because of its higher bandwidth. (explain)

Radeon R9 M275X		72000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 14976 (26%)

Texel Rate

The Radeon R9 M275X should be much (approximately 25%) more effective at AF than the GeForce GT 640 DDR3. (explain)

Radeon R9 M275X		36000 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 7200 (25%)

Pixel Rate

Both cards have exactly the same pixel rate, so in theory they should perform equally good at at AA, and be able to handle the same screen resolutions. (explain)

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 (in units of megabytes per second) that can be transported past the external memory interface in one second. It's worked out by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's 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 amount of texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

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