ATI Radeon HD 3870 X2 review
 

The ATI Radeon HD 3870 X2 is essentially two Radeon HD 3870 GPUs stuck together on the same PCB is meant to be a 'transparent' single card solution, it doesn't require a supporting motherboard. The GPUs use a PCI Express 1.1 bridge to communicate in much the same way Crossfire ATI cards would. However, because the X2 is meant to be a 'transparent' single card solution, it doesn't require a supporting motherboard, and in fact it opens the possibility for quad-Crossfire using two of these graphics cards.

http://www.techspot.com/review/86-at...on-hd-3870-x2/