Radeon HD 3870 1GB vs Radeon HD 6850

Intro

Compare those specifications to the Radeon HD 6850, which has clock speeds of 775 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 memory. It features 960 SPUs as well as 48 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 1GB		106 Watts
Radeon HD 6850		127 Watts
	Difference: 21 Watts (20%)

Memory Bandwidth

In theory, the Radeon HD 6850 will be 78% quicker than the Radeon HD 3870 1GB in general, because of its greater bandwidth. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 3870 1GB		72000 MB/sec
	Difference: 56000 (78%)

Texel Rate

The Radeon HD 6850 should be quite a bit (about 200%) better at AF than the Radeon HD 3870 1GB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 24800 (200%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6850 is a better choice, by a large margin. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 12400 (100%)

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 maximum amount of data (in units of megabytes per second) that can be transferred past the external memory interface within a second. The number is calculated by multiplying the interface width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out 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 rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.