Radeon HD 4650 512MB vs Radeon HD 6770 1GB

Intro

Compare that to the Radeon HD 6770 1GB, which comes with a GPU core clock speed of 900 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 128-bit bus. It also features 800 SPUs, 40 TAUs, 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 6770 1GB		108 Watts
	Difference: 53 Watts (96%)

Memory Bandwidth

In theory, the Radeon HD 6770 1GB will be 320% faster than the Radeon HD 4650 512MB in general, because of its greater bandwidth. (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 is a lot (about 88%) faster with regards to AF 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

The Radeon HD 6770 1GB is a lot (more or less 200%) faster with regards to FSAA than the Radeon HD 4650 512MB, and should be capable of handling higher screen resolutions more effectively. (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: Memory bandwidth is the maximum amount of information (measured in megabytes per second) that can be transported over the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core clock 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 in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.