Radeon HD 4870 X2 vs Radeon HD 6990

Intro

Compare those specs to the Radeon HD 6990, which features core speeds of 830 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 memory. It features 1536 SPUs as well as 96 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 X2		350 Watts
Radeon HD 6990		375 Watts
	Difference: 25 Watts (7%)

Memory Bandwidth

The Radeon HD 6990, in theory, should perform much faster than the Radeon HD 4870 X2 in general. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4870 X2		230400 MB/sec
	Difference: 89600 (39%)

Texel Rate

The Radeon HD 6990 should be a lot (more or less 166%) more effective at AF than the Radeon HD 4870 X2. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 99360 (166%)

Pixel Rate

If running with lots of anti-aliasing 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 4870 X2		24000 Mpixels/sec
	Difference: 29120 (121%)

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 max amount of data (counted in megabytes per second) that can be transported over the external memory interface within a second. The number is calculated by multiplying the interface width by the speed of its memory. In the case of DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better 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 applied in one second. This is calculated by multiplying the total number of texture units of the card 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 a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.