Radeon HD 4650 512MB vs Radeon HD 6750 1GB

Intro

Compare all that to the Radeon HD 6750 1GB, which features clock speeds of 725 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 memory. It features 720 SPUs as well as 36 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 6750 1GB		86 Watts
	Difference: 31 Watts (56%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6750 1GB should perform quite a bit faster than the Radeon HD 4650 512MB in general. (explain)

Radeon HD 6750 1GB		64000 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 48000 (300%)

Texel Rate

The Radeon HD 6750 1GB will be a lot (approximately 36%) faster with regards to AF than the Radeon HD 4650 512MB. (explain)

Radeon HD 6750 1GB		26100 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 6900 (36%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 6750 1GB is the winner, and very much so. (explain)

Radeon HD 6750 1GB		11600 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 6800 (142%)

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 largest amount of information (measured in MB per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. If it uses DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 number of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total texture units by the core speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.