GeForce GT 640 DDR3 vs Radeon HD 4830 512MB

Intro

Compare those specs to the Radeon HD 4830 512MB, which has a GPU core clock speed of 575 MHz, and 512 MB of GDDR3 RAM running at 900 MHz through a 256-bit bus. It also is made up of 640(128x5) Stream Processors, 32 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 4830 512MB		95 Watts
	Difference: 30 Watts (46%)

Memory Bandwidth

Performance-wise, the Radeon HD 4830 512MB should in theory be a bit better than the GeForce GT 640 DDR3 in general. (explain)

Radeon HD 4830 512MB		57600 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 576 (1%)

Texel Rate

The GeForce GT 640 DDR3 will be much (approximately 57%) better at texture filtering than the Radeon HD 4830 512MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4830 512MB		18400 Mtexels/sec
	Difference: 10400 (57%)

Pixel Rate

The GeForce GT 640 DDR3 will be much (about 57%) more effective at AA than the Radeon HD 4830 512MB, and should be capable of handling higher screen resolutions without losing too much performance. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 5200 (57%)

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 max amount of data (counted in megabytes per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total amount of texture units of the card by the core 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 a second.

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