Radeon HD 3850 256MB vs Radeon HD 3870 512MB

Intro

Compare all that to the Radeon HD 3870 512MB, which features a core clock frequency of 775 MHz and a GDDR3 memory speed of 900 MHz. It also uses a 256-bit bus, and uses a 55 nm design. It is made up of 320(64x5) SPUs, 16 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 3870 512MB		106 Watts
	Difference: 31 Watts (41%)

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 512MB should theoretically be a little bit superior to the Radeon HD 3850 256MB in general. (explain)

Radeon HD 3870 512MB		57600 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 4608 (9%)

Texel Rate

The Radeon HD 3870 512MB will be a bit (more or less 16%) more effective at AF than the Radeon HD 3850 256MB. (explain)

Radeon HD 3870 512MB		12400 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 1712 (16%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 3870 512MB is superior to the Radeon HD 3850 256MB, but it probably won't make a huge difference. (explain)

Radeon HD 3870 512MB		12400 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 1712 (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: Bandwidth is the maximum amount of information (measured in MB per second) that can be transported past the external memory interface within a second. The number is calculated by multiplying the bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total texture units by the core 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 applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units 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 fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.