GeForce GT 640 DDR3 vs Radeon HD 5830

Intro

Compare those specifications to the Radeon HD 5830, which features GPU core speed of 800 MHz, and 1024 MB of GDDR5 RAM running at 1000 MHz through a 256-bit bus. It also is comprised of 1120(224x5) Stream Processors, 56 Texture Address Units, and 16 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 HD 5830		175 Watts
	Difference: 110 Watts (169%)

Memory Bandwidth

Theoretically, the Radeon HD 5830 should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

Radeon HD 5830		128000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 70976 (124%)

Texel Rate

The Radeon HD 5830 should be quite a bit (more or less 56%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)

Radeon HD 5830		44800 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 16000 (56%)

Pixel Rate

The GeForce GT 640 DDR3 will be just a bit (about 13%) better at FSAA than the Radeon HD 5830, and also should be capable of handling higher resolutions better. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 5830		12800 Mpixels/sec
	Difference: 1600 (13%)

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 data (in units of MB per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.