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

Intro

Compare all of that to the Radeon HD 4850 X2 1GB, which makes use of a 55 nm design. AMD has set the core speed at 625 MHz. The GDDR3 RAM works at a speed of 993 MHz on this 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 3850 1GB		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% faster than the Radeon HD 3850 1GB overall, because of its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 4850 X2 1GB should be a lot (about 368%) more effective at AF than the Radeon HD 3850 1GB. (explain)

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

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 4850 X2 1GB is the winner, and very much so. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 3850 1GB		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: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be transferred over the external memory interface within a second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR type memory, the result 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, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.