GeForce GT 640 DDR3 vs Radeon HD 4650 512MB

Intro

Compare all that to the Radeon HD 4650 512MB, which comes with core clock speeds of 600 MHz on the GPU, and 500 MHz on the 512 MB of DDR2 RAM. It features 320(64x5) SPUs as well as 32 Texture Address Units and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 10 Watts (18%)

Memory Bandwidth

Theoretically, the GeForce GT 640 DDR3 should perform much faster than the Radeon HD 4650 512MB in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 41024 (256%)

Texel Rate

The GeForce GT 640 DDR3 will be much (approximately 50%) better at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 9600 (50%)

Pixel Rate

If using a high resolution is important to you, then the GeForce GT 640 DDR3 is the winner, by a large margin. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 9600 (200%)

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 (measured in megabytes per second) that can be moved across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it should 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 AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.