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

Intro

Compare that to the Radeon HD 4850 X2 1GB, which has core clock speeds of 625 MHz on the GPU, and 993 MHz on the 1024 MB of GDDR3 RAM. 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

Theoretically, the Radeon HD 4850 X2 1GB should perform a bit faster than the Radeon HD 3870 X2 512MB in general. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 11904 (10%)

Texel Rate

The Radeon HD 4850 X2 1GB should be a lot (approximately 89%) faster with regards to anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 23600 (89%)

Pixel Rate

The Radeon HD 3870 X2 512MB should be a lot (about 32%) faster with regards to anti-aliasing than the Radeon HD 4850 X2 1GB, and also able to handle higher resolutions while still performing well. (explain)

Radeon HD 3870 X2 512MB		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 max amount of information (counted in megabytes per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher 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 texture map elements (texels) that are applied per second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.