Radeon HD 4890 1GB vs Radeon HD 6770

Intro

Compare those specifications to the Radeon HD 6770, which comes with GPU core speed of 900 MHz, and 512 MB of GDDR5 memory running at 1050 MHz through a 128-bit bus. It also features 800 SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

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

Memory Bandwidth

As far as performance goes, the Radeon HD 4890 1GB should in theory be a lot superior to the Radeon HD 6770 in general. (explain)

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

Texel Rate

The Radeon HD 4890 1GB is just a bit (more or less 11%) more effective at texture filtering than the Radeon HD 6770. (explain)

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

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 4890 1GB is the winner, but not by far. (explain)

Radeon HD 4890 1GB		16000 Mpixels/sec
Radeon HD 6770		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: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the core 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 quite a few 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.