[Chiphell]nVidia 9800GX2 PCB Photo

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ATi's solution isn't innovative... It's been done before.

Think 3dfx first. There's also been dual-gpu nvidia solutions that were single pcb. The dual 7800gt from asus comes to mind, for example.

It's been done before.

Yes,it's been done but 3870X2 has native crossfire support on the card itself.

The card itself has a chip (PLX) which provides the communication
between the two Gpus.
So you don't need a Crossfire supporting mobo to use it.
(HD 2600XT used the same way )

But Asus Dual 7800Gt or earlier the Gigabyte Dual 6600GT were communicating over the nortbridge,you needed to use SLI supporting chipsets.And as far as I know those solutions weren't supported officialy by Nvidia.This means no real driver support.
Since 3dfx Nvidia only released ''sandwich'' solutions like 7950GX2 and 9800GX2...