Radeon HD 4650 512MB vs Radeon HD 6750 1GB

Intro

Compare those specifications to the Radeon HD 6750 1GB, which comes with a GPU core clock speed of 725 MHz, and 1024 MB of GDDR5 memory running at 1000 MHz through a 128-bit bus. It also features 720 SPUs, 36 TAUs, and 16 Raster Operation Units.

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

In theory, the Radeon HD 6750 1GB should be 300% quicker than the Radeon HD 4650 512MB in general, because of its higher data rate. (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 is a lot (more or less 36%) more effective at anisotropic filtering 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

The Radeon HD 6750 1GB is a lot (more or less 142%) better at FSAA than the Radeon HD 4650 512MB, and will be capable of handling higher screen resolutions better. (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 data (in units of megabytes per second) that can be transferred past the external memory interface in one second. It is worked out by multiplying the bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 can be applied in one second. This figure 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 card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.