GeForce 8600 GT 512MB GDDR3 vs Radeon HD 6990

Intro

Compare all that to the Radeon HD 6990, which features a clock speed of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit memory bus, and makes use of a 40 nm design. It 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 512MB GDDR3		47 Watts
Radeon HD 6990		375 Watts
	Difference: 328 Watts (698%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6990 is 1329% quicker than the GeForce 8600 GT 512MB GDDR3 in general, due to its greater data rate. (explain)

Radeon HD 6990		320000 MB/sec
GeForce 8600 GT 512MB GDDR3		22400 MB/sec
	Difference: 297600 (1329%)

Texel Rate

The Radeon HD 6990 should be quite a bit (about 1744%) faster with regards to AF than the GeForce 8600 GT 512MB GDDR3. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce 8600 GT 512MB GDDR3		8640 Mtexels/sec
	Difference: 150720 (1744%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 6990 is the winner, by far. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce 8600 GT 512MB 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 data (measured in megabytes per second) that can be moved over the external memory interface in a second. The number is worked out by multiplying the card's interface width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied 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 video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its 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 clock 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 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 maximum fill rate.