Radeon HD 3850 256MB vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which features a clock frequency of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit bus, and uses a 40 nm design. It features 1536 SPUs, 96 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 6990		375 Watts
	Difference: 300 Watts (400%)

Memory Bandwidth

The Radeon HD 6990 should theoretically perform a lot faster than the Radeon HD 3850 256MB in general. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 267008 (504%)

Texel Rate

The Radeon HD 6990 should be a lot (approximately 1391%) more effective at AF than the Radeon HD 3850 256MB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 148672 (1391%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6990 is a better choice, and very much so. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 42432 (397%)

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 information (counted in MB per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the bus width by its memory clock speed. If it uses DDR RAM, it 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, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total number of texture units of the card by the core clock 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 processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.