Radeon HD 3650 256MB vs Radeon HD 4650 1GB

Intro

Compare those specs to the Radeon HD 4650 1GB, which has a GPU core clock speed of 600 MHz, and 1024 MB of GDDR3 RAM set to run at 700 MHz through a 128-bit bus. It also is comprised of 320(64x5) Stream Processors, 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 1GB		55 Watts
Radeon HD 3650 256MB		78 Watts
	Difference: 23 Watts (42%)

Memory Bandwidth

In theory, the Radeon HD 3650 256MB should be a little bit faster than the Radeon HD 4650 1GB in general. (explain)

Radeon HD 3650 256MB		25600 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 3200 (14%)

Texel Rate

The Radeon HD 4650 1GB is a lot (more or less 231%) faster with regards to AF than the Radeon HD 3650 256MB. (explain)

Radeon HD 4650 1GB		19200 Mtexels/sec
Radeon HD 3650 256MB		5800 Mtexels/sec
	Difference: 13400 (231%)

Pixel Rate

The Radeon HD 4650 1GB is quite a bit (more or less 66%) more effective at AA than the Radeon HD 3650 256MB, and also will be capable of handling higher resolutions better. (explain)

Radeon HD 4650 1GB		4800 Mpixels/sec
Radeon HD 3650 256MB		2900 Mpixels/sec
	Difference: 1900 (66%)

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 largest amount of information (measured in MB per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per 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 number is worked out by multiplying the number of Render Output Units by the the core 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 fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.