Radeon HD 3850 256MB vs Radeon HD 4850 X2 512MB

Intro

Compare that to the Radeon HD 4850 X2 512MB, which features GPU clock speed of 625 MHz, and 512 MB of GDDR3 memory set to run at 993 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 175 Watts (233%)

Memory Bandwidth

The Radeon HD 4850 X2 512MB should in theory be much faster than the Radeon HD 3850 256MB overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 74112 (140%)

Texel Rate

The Radeon HD 4850 X2 512MB should be a lot (approximately 368%) better at anisotropic filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 39312 (368%)

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 3850 256MB		10688 Mpixels/sec
	Difference: 9312 (87%)

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: Bandwidth is the maximum amount of data (counted in megabytes per second) that can be moved across the external memory interface in one second. The number is calculated by multiplying the bus width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's 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 amount of texture map elements (texels) that can be processed per second. This number is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the 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 most pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units 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 rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.