Radeon HD 3850 X2 vs Radeon HD 4850 512MB

Intro

Compare those specs to the Radeon HD 4850 512MB, which features a GPU core clock speed of 625 MHz, and 512 MB of GDDR3 memory running at 993 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the Radeon HD 3850 X2 should in theory be much superior to the Radeon HD 4850 512MB in general. (explain)

Radeon HD 3850 X2		105984 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 42432 (67%)

Texel Rate

The Radeon HD 4850 512MB is just a bit (about 17%) faster with regards to anisotropic filtering than the Radeon HD 3850 X2. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 3624 (17%)

Pixel Rate

The Radeon HD 3850 X2 should be a lot (more or less 114%) more effective at FSAA than the Radeon HD 4850 512MB, and also able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 11376 (114%)

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 transferred across the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory speed. In the case of DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.