Radeon HD 4890 2GB vs Radeon HD 6770 1GB

Intro

Compare those specs to the Radeon HD 6770 1GB, which comes with a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 128-bit bus, and uses a 40 nm design. It features 800 SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770 1GB		108 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 82 Watts (76%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4890 2GB should perform a lot faster than the Radeon HD 6770 1GB overall. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 57600 (86%)

Texel Rate

The Radeon HD 4890 2GB is a small bit (more or less 11%) better at anisotropic filtering than the Radeon HD 6770 1GB. (explain)

Radeon HD 4890 2GB		40000 Mtexels/sec
Radeon HD 6770 1GB		36000 Mtexels/sec
	Difference: 4000 (11%)

Pixel Rate

The Radeon HD 4890 2GB will be just a bit (more or less 11%) faster with regards to anti-aliasing than the Radeon HD 6770 1GB, and will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 4890 2GB		16000 Mpixels/sec
Radeon HD 6770 1GB		14400 Mpixels/sec
	Difference: 1600 (11%)

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 max amount of data (counted in megabytes per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total 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 applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.