Radeon HD 4890 2GB vs Radeon HD 6990

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
Radeon HD 6990		375 Watts
	Difference: 185 Watts (97%)

Memory Bandwidth

The Radeon HD 6990 should theoretically perform much faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 195200 (156%)

Texel Rate

The Radeon HD 6990 should be quite a bit (more or less 298%) faster with regards to texture filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 119360 (298%)

Pixel Rate

The Radeon HD 6990 will be much (about 232%) faster with regards to FSAA than the Radeon HD 4890 2GB, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 37120 (232%)

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 megabytes per second) that can be transferred past the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 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 anti-aliasing, HDR and high resolutions.

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

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