Radeon HD 4650 512MB vs Radeon HD 6770 1GB

Intro

Compare those specs to the Radeon HD 6770 1GB, which uses a 40 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 RAM runs at a frequency of 1050 MHz on this particular model. It features 800 SPUs as well as 40 TAUs and 16 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 6770 1GB		108 Watts
	Difference: 53 Watts (96%)

Memory Bandwidth

The Radeon HD 6770 1GB should theoretically perform a lot faster than the Radeon HD 4650 512MB overall. (explain)

Radeon HD 6770 1GB		67200 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 51200 (320%)

Texel Rate

The Radeon HD 6770 1GB will be much (about 88%) better at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 16800 (88%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 6770 1GB is the winner, by far. (explain)

Radeon HD 6770 1GB		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 largest amount of information (measured in MB per second) that can be moved across the external memory interface in a second. The number is worked out by multiplying the bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 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 high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This is calculated by multiplying the total texture units by the core speed of the chip. The better the texel rate, the better the video card will be at handling 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 the video card could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's 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 fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.