Radeon HD 3850 256MB vs Radeon HD 3870 512MB

Intro

Compare those specifications to the Radeon HD 3870 512MB, which features GPU clock speed of 775 MHz, and 512 MB of GDDR3 RAM running at 900 MHz through a 256-bit bus. It also 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

Performance-wise, the Radeon HD 3870 512MB should in theory be a small bit better than the Radeon HD 3850 256MB overall. (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 should be a small bit (approximately 16%) better at anisotropic filtering 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 running with a high screen resolution is important to you, then the Radeon HD 3870 512MB is superior to the Radeon HD 3850 256MB, though only just barely. (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: Memory bandwidth is the max amount of information (measured in megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

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