Radeon HD 4890 2GB vs Radeon HD 6770 1GB

Intro

Compare those specifications to the Radeon HD 6770 1GB, which features core speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 RAM. It features 800 SPUs along with 40 TAUs 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

Performance-wise, the Radeon HD 4890 2GB should in theory be a lot superior to 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 will be a bit (about 11%) more effective 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 is a little bit (about 11%) more effective at AA than the Radeon HD 6770 1GB, and also should be capable of handling higher screen resolutions better. (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 maximum amount of data (in units of megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate 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 drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.