Radeon HD 3850 256MB vs Radeon HD 3870 512MB

Intro

Compare those specifications to the Radeon HD 3870 512MB, which makes use of a 55 nm design. AMD has set the core speed at 775 MHz. The GDDR3 RAM works at a speed of 900 MHz on this specific card. It features 320(64x5) SPUs as well as 16 Texture Address Units and 16 Rasterization Operator 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

The Radeon HD 3870 512MB should in theory perform a small bit faster 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 little bit (more or less 16%) more effective 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

The Radeon HD 3870 512MB should be a small bit (approximately 16%) more effective at full screen anti-aliasing than the Radeon HD 3850 256MB, and also will be able to handle higher resolutions better. (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 largest amount of data (in units of MB per second) that can be transferred across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The higher the texel rate, the better the 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 number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out 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 outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.