It looks like doubling up processors isn’t going to be limited to PC chips, as Asus is moving forward with plans to offer the EN6800GT, a single graphics card with two (separate, not dual-core) Nvidia 6800 GT chips built-in. That means all the power of SLI in a single, expensive purchase, but as you can see from The Inquirer’s photo of the prototype board, it’s not going to be tiny.
https://gizmodo.com/dual-core-round-up-102129
This card should be cheaper than two 6800GTs, but I wouldn’t be surprised if Asus charges an extra premium to be the first to provide such a configuration, putting this in the $600-700 range.
Asus Double 6800GT almost ready [TheInquirer]