Radeon HD 3850 256MB vs Radeon HD 4850 X2 1GB

Intro

Compare that to the Radeon HD 4850 X2 1GB, which uses a 55 nm design. AMD has set the core frequency at 625 MHz. The GDDR3 RAM is set to run at a frequency of 993 MHz on this card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

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 1GB		250 Watts
	Difference: 175 Watts (233%)

Memory Bandwidth

In theory, the Radeon HD 4850 X2 1GB should be 140% quicker than the Radeon HD 3850 256MB overall, due to its greater bandwidth. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 74112 (140%)

Texel Rate

The Radeon HD 4850 X2 1GB should be quite a bit (approximately 368%) more effective at AF than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 39312 (368%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 4850 X2 1GB is the winner, by a large margin. (explain)

Radeon HD 4850 X2 1GB		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 largest amount of information (counted in megabytes per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the bus width by its memory speed. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most 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 worked out by multiplying the amount of Raster Operations Pipelines by the clock 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 also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.