GeForce 8600 GT 1GB GDDR3 vs Radeon HD 6990

Intro

Compare those specifications to the Radeon HD 6990, which has GPU clock speed of 830 MHz, and 2048 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also is made up of 1536 SPUs, 96 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 1GB GDDR3		47 Watts
Radeon HD 6990		375 Watts
	Difference: 328 Watts (698%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6990 should theoretically be much superior to the GeForce 8600 GT 1GB GDDR3 overall. (explain)

Radeon HD 6990		320000 MB/sec
GeForce 8600 GT 1GB GDDR3		22400 MB/sec
	Difference: 297600 (1329%)

Texel Rate

The Radeon HD 6990 should be quite a bit (approximately 1744%) better at AF than the GeForce 8600 GT 1GB GDDR3. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce 8600 GT 1GB GDDR3		8640 Mtexels/sec
	Difference: 150720 (1744%)

Pixel Rate

The Radeon HD 6990 will be a lot (approximately 1130%) more effective at FSAA than the GeForce 8600 GT 1GB GDDR3, and also should be capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce 8600 GT 1GB GDDR3		4320 Mpixels/sec
	Difference: 48800 (1130%)

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 largest amount of information (counted in MB per second) that can be moved over the external memory interface in a second. It's worked out 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 higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly write 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 clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.