Radeon HD 4870 1GB vs Radeon HD 6990

Intro

Compare those specifications to the Radeon HD 6990, which uses a 40 nm design. AMD has set the core speed at 830 MHz. The GDDR5 memory is set to run at a speed of 1250 MHz on this particular model. It features 1536 SPUs along with 96 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 1GB		150 Watts
Radeon HD 6990		375 Watts
	Difference: 225 Watts (150%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6990 should theoretically be quite a bit superior to the Radeon HD 4870 1GB in general. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 204800 (178%)

Texel Rate

The Radeon HD 6990 is quite a bit (approximately 431%) more effective at texture filtering than the Radeon HD 4870 1GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 129360 (431%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6990 is the winner, and very much so. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 41120 (343%)

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 (in units of megabytes per second) that can be transported past the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory speed. In the case of DDR 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 anti-aliasing, High Dynamic Range and high 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 this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.