There are two PCIexpreX1 slots on the motherboard and I think probably I can run the third card by the extension cable.I bought one from cablesaures
PCIe x1 -> x16 Adapter Extender Cable
https://cablesaurus.com/index.php?main_page=product_info&cPath=1&products_id=10
But I am not sure how to connect them together. Could anyone be kind enough to give me some instruction?
I took two pictures but do not know how to upload it. I posted the link@picasa here
https://picasaweb.google.com/104501255284307964408/20110719?authkey=Gv1sRgCNeS1pmZyYHUigE#5631122665237192994
https://picasaweb.google.com/104501255284307964408/20110719?authkey=Gv1sRgCNeS1pmZyYHUigE#5631122679902177426