3-Way SLI high end rig can cost up over $8000
 

There are only two versions of VGA card that supports 3-way SLI: The 8800GTX and 8800Ultra. What’s more, NVIDIA requires a platform like this to play with 3-way SLI.<br>
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* Intel Core 2 Quad<br>
* NVIDIA nForce 680i/780i<br>
* 2GB DDR2-800 <br>
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And you can not use a 15 inch monitor while you using such a expensive platform. An 24inch LCD is minimum.

http://en.expreview.com/?p=146&page=1