Radeon HD 3850 X2 vs Radeon HD 6990

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 6990 should theoretically be quite a bit superior to the Radeon HD 3850 X2 overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 3850 X2		105984 MB/sec
	Difference: 214016 (202%)

Texel Rate

The Radeon HD 6990 should be quite a bit (approximately 646%) faster with regards to texture filtering than the Radeon HD 3850 X2. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 137984 (646%)

Pixel Rate

The Radeon HD 6990 is quite a bit (about 149%) faster with regards to FSAA than the Radeon HD 3850 X2, and will be able to handle higher resolutions while still performing well. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 3850 X2		21376 Mpixels/sec
	Difference: 31744 (149%)

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 information (measured in MB per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record 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 the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.