Radeon HD 4890 1GB vs Radeon HD 6770 1GB

Intro

Compare all that to the Radeon HD 6770 1GB, which makes use of a 40 nm design. AMD has set the core frequency at 900 MHz. The GDDR5 RAM is set to run at a frequency of 1050 MHz on this specific model. It features 800 SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

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

Memory Bandwidth

Theoretically speaking, the Radeon HD 4890 1GB should be 86% faster than the Radeon HD 6770 1GB overall, due to its greater bandwidth. (explain)

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

Texel Rate

The Radeon HD 4890 1GB should be a bit (about 11%) more effective at AF than the Radeon HD 6770 1GB. (explain)

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

Pixel Rate

The Radeon HD 4890 1GB will be just a bit (approximately 11%) faster with regards to full screen anti-aliasing than the Radeon HD 6770 1GB, and capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 4890 1GB		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 maximum amount of information (measured in MB per second) that can be transferred past the external memory interface in one second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.