Radeon HD 3870 512MB vs Radeon HD 6870

Intro

Compare that to the Radeon HD 6870, which comes with GPU core speed of 900 MHz, and 1024 MB of GDDR5 memory running at 1050 MHz through a 256-bit bus. It also features 1120 SPUs, 56 Texture Address Units, and 32 ROPs.

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

The Radeon HD 6870 should in theory perform much faster than the Radeon HD 3870 512MB overall. (explain)

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

Texel Rate

The Radeon HD 6870 should be quite a bit (approximately 306%) more effective at anisotropic 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

If using lots of anti-aliasing is important to you, then the Radeon HD 6870 is a better choice, by a large margin. (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 maximum amount of information (in units of megabytes per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better 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 texture map elements (texels) that can be processed per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.