Radeon HD 4650 512MB vs Radeon HD 6950 2GB

Intro

Compare all of that to the Radeon HD 6950 2GB, which has core speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1408 SPUs along with 88 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 6950 2GB		200 Watts
	Difference: 145 Watts (264%)

Memory Bandwidth

Theoretically, the Radeon HD 6950 2GB should be quite a bit faster than the Radeon HD 4650 512MB in general. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 144000 (900%)

Texel Rate

The Radeon HD 6950 2GB is a lot (about 267%) more effective at AF than the Radeon HD 4650 512MB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 51200 (267%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6950 2GB is the winner, by a large margin. (explain)

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 20800 (433%)

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 transported across the external memory interface in a second. The number is calculated by multiplying the interface width by the speed of its memory. If it uses DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster 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 texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.