Besides running two identical cards the board and Powercolor card are both PCI-E 2.0 while the Asus card is 1.0?
The Asus is an older card being marked down pricewise and won't meet the 2.0 requirements to start with for the newer boards out. For plans on seeing a Crossfire setup two identical cards are required just as seen with SLI on nForce boards with NVidia driven cards.
What are you talking about? The card you are referring to is not a video card PC eye, it a AGEIA PhysX card. He is wanting to know if he can run 2 4670 in crossfire with the PhysX card in the third slot. The answer is YES.