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

Intro

Compare those specifications to the Radeon HD 4850 1GB, which comes with core speeds of 625 MHz on the GPU, and 993 MHz on the 1024 MB of GDDR4 memory. It features 800(160x5) SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 1GB should be 127% faster than the Radeon HD 4850 1GB overall, due to its greater bandwidth. (explain)

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

Texel Rate

The Radeon HD 3870 X2 1GB is a bit (about 6%) more effective at anisotropic filtering than the Radeon HD 4850 1GB. (explain)

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

Pixel Rate

The Radeon HD 3870 X2 1GB should be a lot (more or less 164%) faster with regards to FSAA than the Radeon HD 4850 1GB, and able to handle higher resolutions while still performing well. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 4850 1GB		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: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video 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 amount of 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 is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.