GeForce 8600 GT 1GB GDDR3 vs Radeon HD 7990

Intro

Compare that to the Radeon HD 7990, which features GPU core speed of 950 MHz, and 3072 MB of GDDR5 memory set to run at 1500 MHz through a 384-bit bus. It also is comprised of 2048 SPUs, 128 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 7990		375 Watts
	Difference: 328 Watts (698%)

Memory Bandwidth

The Radeon HD 7990 should in theory perform quite a bit faster than the GeForce 8600 GT 1GB GDDR3 in general. (explain)

Radeon HD 7990		576000 MB/sec
GeForce 8600 GT 1GB GDDR3		22400 MB/sec
	Difference: 553600 (2471%)

Texel Rate

The Radeon HD 7990 is much (about 2715%) faster with regards to AF than the GeForce 8600 GT 1GB GDDR3. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce 8600 GT 1GB GDDR3		8640 Mtexels/sec
	Difference: 234560 (2715%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 7990 is the winner, by a large margin. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce 8600 GT 1GB GDDR3		4320 Mpixels/sec
	Difference: 56480 (1307%)

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: Memory bandwidth is the max amount of data (measured in MB per second) that can be moved over the external memory interface in a second. It's worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better 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 amount of texture map elements (texels) that can be processed per second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, 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 amount of pixels that the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.