The technicians from Sapphire have had some hard work to get two R350 chips on one card, especially problems of thermal nature. This card is far from mainstream production process, and most likely it will never hit the shops.
But they write that it still remains extremely interesting that Sapphire has been able to develop this type of technology. Maybe in future they will be experimenting even more with multichip solutions, so maybe we can expect a dual chip R420 card from Sapphire.
If those things will ever retail then one thing is sure ; these will be extremely expensive.
Source : Hardware Upgrade