Radeon HD 3870 X2 1GB vs Radeon HD 4850 512MB

Intro

Compare those specifications to the Radeon HD 4850 512MB, which has clock speeds of 625 MHz on the GPU, and 993 MHz on the 512 MB of GDDR3 memory. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3870 X2 1GB should theoretically be quite a bit superior to the Radeon HD 4850 512MB in general. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 80576 (127%)

Texel Rate

The Radeon HD 3870 X2 1GB is a small bit (approximately 6%) more effective at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 3870 X2 1GB		26400 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 1400 (6%)

Pixel Rate

The Radeon HD 3870 X2 1GB should be quite a bit (more or less 164%) better at FSAA than the Radeon HD 4850 512MB, and will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 16400 (164%)

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 maximum amount of information (measured in megabytes per second) that can be transferred across the external memory interface in a second. It's calculated by multiplying the interface width by its memory speed. If the card has DDR type RAM, the result should be multiplied by 2 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, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.