Radeon HD 4850 512MB vs Radeon HD 4850 X2 512MB

Intro

Compare that to the Radeon HD 4850 X2 512MB, which makes use of a 55 nm design. AMD has set the core speed at 625 MHz. The GDDR3 memory works at a frequency of 993 MHz on this specific card. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 512MB		110 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 140 Watts (127%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 X2 512MB is 100% faster than the Radeon HD 4850 512MB overall, because of its greater bandwidth. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 63552 (100%)

Texel Rate

The Radeon HD 4850 X2 512MB will be a lot (about 100%) faster with regards to anisotropic filtering than the Radeon HD 4850 512MB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 25000 (100%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 4850 X2 512MB is the winner, and very much so. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 10000 (100%)

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 largest amount of data (measured in megabytes per second) that can be transferred across the external memory interface in a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the 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 number of pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.