GeForce GT 640 DDR3 vs Radeon HD 5850

Intro

Compare all of that to the Radeon HD 5850, which has clock speeds of 725 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 memory. It features 1440(288x5) SPUs along with 72 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 5850		151 Watts
	Difference: 86 Watts (132%)

Memory Bandwidth

Theoretically, the Radeon HD 5850 should be much faster than the GeForce GT 640 DDR3 overall. (explain)

Radeon HD 5850		128000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 70976 (124%)

Texel Rate

The Radeon HD 5850 is quite a bit (about 81%) faster with regards to anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Radeon HD 5850		52200 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 23400 (81%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 5850 is the winner, and very much so. (explain)

Radeon HD 5850		23200 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 8800 (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: Bandwidth is the maximum amount of information (in units of MB per second) that can be transferred across the external memory interface in one second. It's worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the graphics 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 chip could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.