Radeon HD 3870 1GB vs Radeon HD 6770 1GB

Intro

Compare those specifications to the Radeon HD 6770 1GB, which has 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 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 1GB		106 Watts
Radeon HD 6770 1GB		108 Watts
	Difference: 2 Watts (2%)

Memory Bandwidth

In theory, the Radeon HD 3870 1GB will be 7% faster than the Radeon HD 6770 1GB overall, due to its higher bandwidth. (explain)

Radeon HD 3870 1GB		72000 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 4800 (7%)

Texel Rate

The Radeon HD 6770 1GB is quite a bit (about 190%) more effective at texture filtering than the Radeon HD 3870 1GB. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 23600 (190%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 6770 1GB is the winner, but it probably won't make a huge difference. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 2000 (16%)

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 past the external memory interface in a second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

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