Radeon HD 3850 256MB vs Radeon HD 3870 X2 512MB

Intro

Compare that to the Radeon HD 3870 X2 512MB, which makes use of a 55 nm design. AMD has clocked the core frequency at 825 MHz. The GDDR3 RAM runs at a speed of 900 MHz on this particular model. It features 320(64x5) SPUs along with 16 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 512MB will be 117% faster than the Radeon HD 3850 256MB overall, because of its greater data rate. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 62208 (117%)

Texel Rate

The Radeon HD 3870 X2 512MB is quite a bit (approximately 147%) better at texture filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 15712 (147%)

Pixel Rate

The Radeon HD 3870 X2 512MB is a lot (more or less 147%) faster with regards to AA than the Radeon HD 3850 256MB, and should be capable of handling higher screen resolutions better. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 15712 (147%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (in units of MB per second) that can be transferred past the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.