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

Intro

Compare those specifications to the Radeon HD 4850 X2 1GB, which features a clock frequency of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 1GB should theoretically be a bit superior to the Radeon HD 4850 X2 1GB overall. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 17024 (13%)

Texel Rate

The Radeon HD 4850 X2 1GB will be much (more or less 89%) better at anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 23600 (89%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 3870 X2 1GB is the winner, by a large margin. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 6400 (32%)

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 maximum amount of data (in units of megabytes per second) that can be moved over the external memory interface in a second. The number is calculated by multiplying the bus width by its memory clock speed. In the case of DDR RAM, it should be multiplied by 2 once 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 can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

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