Radeon HD 3870 X2 512MB vs Radeon HD 5850

Intro

Compare those specifications to the Radeon HD 5850, which comes with a GPU core clock speed of 725 MHz, and 1024 MB of GDDR5 memory running at 1000 MHz through a 256-bit bus. It also features 1440(288x5) SPUs, 72 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 5850 should be a small bit faster than the Radeon HD 3870 X2 512MB overall. (explain)

Radeon HD 5850		128000 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 5850 will be quite a bit (about 98%) better at anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

Radeon HD 5850		52200 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 25800 (98%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 3870 X2 512MB is a better choice, though not by far. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 5850		23200 Mpixels/sec
	Difference: 3200 (14%)

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: Memory bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the interface width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour 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 rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.