Radeon HD 4870 2GB vs Radeon HD 6770 1GB

Intro

Compare all that to the Radeon HD 6770 1GB, which has core speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 800 SPUs as well as 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 4870 2GB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 2GB should in theory be a lot superior to the Radeon HD 6770 1GB overall. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 48000 (71%)

Texel Rate

The Radeon HD 6770 1GB will be a little bit (more or less 20%) faster with regards to anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 6000 (20%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6770 1GB is superior to the Radeon HD 4870 2GB, not by a very large margin though. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 2400 (20%)

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 information (counted in megabytes per second) that can be transferred across 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 it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.