Radeon HD 4850 X2 512MB vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which features a core clock speed of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also makes use of 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

Power Consumption (Max TDP)

Radeon HD 4850 X2 512MB		250 Watts
Radeon HD 6990		375 Watts
	Difference: 125 Watts (50%)

Memory Bandwidth

Theoretically, the Radeon HD 6990 should be a lot faster than the Radeon HD 4850 X2 512MB overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 192896 (152%)

Texel Rate

The Radeon HD 6990 is quite a bit (about 219%) more effective at AF than the Radeon HD 4850 X2 512MB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4850 X2 512MB		50000 Mtexels/sec
	Difference: 109360 (219%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6990 is the winner, by a large margin. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 4850 X2 512MB		20000 Mpixels/sec
	Difference: 33120 (166%)

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 largest amount of information (in units of MB per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, 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 can be processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core 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 in one second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel 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.