GeForce GT 640 DDR3 vs Radeon HD 5850

Intro

Compare all that to the Radeon HD 5850, which uses a 40 nm design. AMD has clocked the core speed at 725 MHz. The GDDR5 memory works at a speed of 1000 MHz on this particular model. It features 1440(288x5) SPUs as well as 72 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 HD 5850		151 Watts
	Difference: 86 Watts (132%)

Memory Bandwidth

In theory, the Radeon HD 5850 is 124% faster than the GeForce GT 640 DDR3 overall, due to its higher data rate. (explain)

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

Texel Rate

The Radeon HD 5850 should be quite a bit (approximately 81%) more effective at AF 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

The Radeon HD 5850 should be a lot (more or less 61%) more effective at anti-aliasing than the GeForce GT 640 DDR3, and will be able to handle higher screen resolutions more effectively. (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: Memory bandwidth is the max amount of information (counted in megabytes per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the bus width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the 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 amount of texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the the core 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 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 get to the maximum fill rate.