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

Intro

Compare that to the Radeon HD 4850 X2 1GB, which features GPU clock speed of 625 MHz, and 1024 MB of GDDR3 RAM set to run at 993 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 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 3870 1GB		106 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 144 Watts (136%)

Memory Bandwidth

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

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 3870 1GB		72000 MB/sec
	Difference: 55104 (77%)

Texel Rate

The Radeon HD 4850 X2 1GB will be much (more or less 303%) more effective at AF than the Radeon HD 3870 1GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 37600 (303%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4850 X2 1GB is a better choice, and very much so. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 7600 (61%)

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 information (measured in megabytes per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the 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 amount of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.