Radeon HD 3870 512MB vs Radeon HD 6870

Intro

Compare those specifications to the Radeon HD 6870, which features GPU clock speed of 900 MHz, and 1024 MB of GDDR5 memory running at 1050 MHz through a 256-bit bus. It also is comprised of 1120 SPUs, 56 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
Radeon HD 6870		151 Watts
	Difference: 45 Watts (42%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6870 should be 133% faster than the Radeon HD 3870 512MB in general, because of its higher bandwidth. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 76800 (133%)

Texel Rate

The Radeon HD 6870 is much (more or less 306%) more effective at texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 38000 (306%)

Pixel Rate

The Radeon HD 6870 should be much (about 132%) better at FSAA than the Radeon HD 3870 512MB, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 3870 512MB		12400 Mpixels/sec
	Difference: 16400 (132%)

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 largest amount of data (in units of megabytes per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR type memory, the result should 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 high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.