The Radeon HD 3870 X2 is instead powered by a pair of RV670 GPUs linked together on a single PCB by a PCI Express fan-out switch. In essence, the Radeon HD 3870 X2 is “CrossFire on a card” but with a small boost in clock speed for each GPU as well.
Reviews: Hothardware, Anandtech, Hardocp.
Expect TechSpot's own take on the Radeon HD 3870 X2 later this week. Unfortunately we were unable to secure a card earlier.