Hold up on the board..... If you take alook the ud3 does n't have dual x16 speed.... It says only 1 at 16 and 1 at 4!
I did the same thing... the description says 2 16 pci-e slots... but nothing else.
PCI Express 2.0 x16: 1 x PCI Express x16 slot, running at x16 (PCIEX16) *For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot. 1 x PCI Express x16 slot, running at x4 (PCIEX4) *When the PCIEX1_2 or PCIEX1_3 slot is populated with an......
Seems boards for xfire sli are over 200 bucks
Edit found 1 for $160
Newegg.com - ASRock P67 Extreme4 LGA 1155 Intel P67 SATA 6Gb/s USB 3.0 ATX Intel Motherboard